My opinion, late though it is, is that I can deal with someone moving trick-or-treating a couple of days in either direction, but I won't like it. Any more than a few days would not have my participation.
I kind of like Halloween, but have not gotten excited about it since I still went trick-or-treating. I hand out candy because that's what you do. I hand out candy with a "Happy Halloween!" whenever the doorbell rings, but it isn't something I do because I think it is fun. I do it because I think it it is nice, and because I remember being a kid who went door to door and ad fun, so I want other kids to have that fun too.
If a city council decided to move Halloween a couple of days, I'd grumble but hand out candy. At that point it feels like "we want the kids to have fun, but want them to stay safe and not be too tired for school". It would annoy me, but I'd participate.
If they moved it more than a few days (to a different week, for example) I'd probably not participate. The further away from the actual date, the less likely I am to participate. At that point the town is intruding on me a bit too much. I'm doing a nice thing by handing out candy and it almost feels like I'm being taken advantage of. Insisting on trick-or-treating a week or so before or after the fact just seems like it is more about free candy than the fun because trick-or-treating is not a necessary part of Halloween. Traditional, yes, but not necessary. If trick or treating was cancelled because of something, some sort of party could be arranged for parents to bring kids to. Kids can still have fun without relying on random neighbors to indulge them.
This all assumes I have not bought the candy. If I bought the candy, I might just put it out on the porch in a bowl and make myself scarce.