I personally think the phone thing would be rude, or at least special snowflake. I don't want a phone so I'm going to make people go out of their way to get a hold of me.
There not making you do anything, it still is your own choice.
[My second bro often has No phone, he is in the tropics and it most often than not fails to work. It doesn't make him rude. He simply found out much later than everyone else when emergancies happen [ Dad's heart attack/ Mum's strokes/ etc. we had to send the info snail mail.]
It could be rude, though. It all depends on the attitude of the phone-less person. If they're like your brother and perfectly willing to learn things later than everyone else and not be in constant contact, they're not rude. If, on the other hand, they want to live the "simple life" without a phone or email or whatever, but still expect everyone to bend over backwards to keep them in the loop, they're definitely being special snowflakes, at the very least. If they not only expect people to take extra effort to contact them but berate them when they don't, they're being rude special snowflakes.
Not being easily contacted is not rude. Not being easily contacted but expecting people to contact you regularly is.
In the case of Dragon 8's brother, it sounds like he couldn't have a phone where he was, not that he didn't want one. If someone in my immediate family were hurt or sick or just got engaged or pregnant, and they chose to announce the fact with a post on Facebook, instead of calling or emailing, I'd take that as a sign that the close bond that I thought we had was in face not at all close. A casual acquaintance announcing news to other casual acquaintances on Facebook? No problem. My sister letting me know she's engaged? Problem. I think the relationship
between the two individuals counts for something here. That's what bothered me in the OP, this is the OP's sister, not a friend, not a co-worker. Your own sister can't pick up the phone or email if she thinks the news is important enough for you to know?
I only got a cell phone a few years ago. It's for emergencies; it's pay-as-you-talk and I keep the minimum number of minutes on it. I no longer give out the number, because, like T'Mar, people assume the cell number is the best one to use to reach me. They can't grasp that the cell phone is turned off 99% of the time. I can't get them to use the landline over the cell, and I have voicemail on the landline. Who's ruder, me for not giving out the number or other people for insisting on calling it, even though I have a landline and email?
I don't always check my personal email daily. I'm trying hard to check it daily, but only once a day. I know this bugs some of my family, but if they really need to contact me, they know that they can pick up the phone and call. What about someone who has a MySpace account and doesn't want a Facebook account?
Years ago, when there was important news, you visited in person or wrote a letter. Word of the news got spread by word of mouth from there.
Technology makes our lives easier in many ways. It shouldn't require us to do more work.