That's perfect! Just the addition of that one sentence or the mention that the area has a history of racial tension takes out any need for automatic implication. It is an innocent question asking about whether someone's culture may have something to do with how they behave. Writing something in a way so people "know what you're getting at" is fine when it is blindingly obvious that race or culture may play a part in mannerisms e.g. not eating meat/drinking alcohol/sharing food - but race as the first reason of the inability of a neighbour to return a hello is not what most people would think of. I actually sincerely doubt that anyone would have asked you if your neighbours were being unfriendly because of their race (if you hadn't mentioned it) until about 20+ other possibilities were exhausted, if at all!. People write threads on here every day about pushy salesmen, annoying co-workers or rude in-laws and no-one ever (rarely) asks if their behaviour can be explained by their race or sexual orientation because the behaviour complained of is SO FAR away from anything where race would ever be relevant that it doesn't cross anyones mind. So if you think it may be relevant, you need to ask so we can take it into account. Your original post didn't talk about their lack of want to integrate with you or the community or culture-spqcific behaviours they have displayed, but about their shunning and unfriendliness towards you instead. In a lack of integration question, people may question race as a possibility but in a lack of saying hello to me, not many people would think racial differences would be the first factor. They'd think it was down to a nasty personality first and foremost so would be confused as to why the mention of their race matters.
My boss telling me "I've hired a new co-worker for the office. He's black. You're all white." would make me think "err....so?" Because race playing a factor in the ability or inability to integrate into an office makes about as much sense as race playing a factor in returning or not returning a friendly hello to a neighbour. I'd ask if the neighbour was senile or saw an offensive bumper sticker of yours as more sensical reasons to not return a hello before I'd even think about that it may be down to a cultural thing. However, with your update, you asked if culture or racial tensions could play a part which then made everything fall into place. Like algebra. It connected the two up and proved there was a valid reason why you mentioned race. Without it, everyone has to go into the dangerous territory of deducing what you meant by bringing it up and inferring without any background information when the behaviour is not one that is widely known to be down to race, sex or disability differences.
Anyway, I'm glad we've made up now. Like Shoo says... lets put this behind us and go forward with the talk of cupcakes. Welcome to the forum! 
The OP never mentioned the race of his neighbors. We do not know if they are black or white. What we do know is that they identify themselves as Haitians. I doubt anyone would have asked what race his neighbors were, but I am sure someone would have asked if there might be a cultural difference that could explain the actions.
That's true. But I reckon the first thing that would cross peoples minds would be that it was to do with their personality (or lack of), not a cultural or race difference. There's tonnes of threads everyday on obnoxious and unfriendly neighbours or co-workers or supermarket cashiers but I rarely any see replies from posters asking what their culture is - in case that could be a factor.
I just don't think one should ever IMPLY anything when it has to do with race, gender, sexual orientation etc... threads should be neutral and objective. Replace 'shunned by our Hatian neighbours for no reason with' 'shunned by my Ethiopian/Jewish/g
ay/Black co-worker for no-reason' and it's the same thing. Without any background information, would you understand why the OP mentioned a personal characteristic?
Why are people saying it's implied? Is it implied that someone of a different culture may be unfriendly to a neighbour and everyone should automatically get what the OP means? If so, I didn't get the implication. There is a massive difference between implied and 'a possibility'. It's a possibility that a neighbour of a different culture might shun the OP due to cultural differences but I definitely don't think it's implied - or should be implied by anyone. To imply means to strongly suggest the possibility of truth. If a poster wrote a thread titled "beaten up by a Mexican man today" without saying anything more on the matter...there would be some people out there who would say 'it was implied why his nationality was included' when the majority of us would surely be horrified that someone was implying it in the first place.
I really don't think it wise to start a debate about this again. We don't want to bother the moderators or get the thread locked - especially when everyone has been so polite and the OP so nice. After the OPs follow up, I completely agree that asking about cultural differences is a valid question. I'm with you there. He just gave no mention of it in his original post which is why I asked him if he was missing something... and he kindly followed up with it. I Understand 100% why he might think it be a 'possibility' but the truth is - like O'dell said, its most likely to do with them being unfriendly and unsociable than their culture.