Sorry to say, but you're the one trying to silence criticism here. All firewing628 is doing is trying to get people to remember there are other great things about the convention to enjoy, such as meeting up with friends you may only get to see once a year. Sure, it'll be disappointing if you're favorite VA can't make it; I'll be slightly disappointed myself if Rebecca Shoichet cant make it, but I'm excited to spend time with friends, some who I'm meeting in person for the first time ever. The guests are the icing on the cake.
I'll admit, it WAS worrying how long it took for guests to first be announced, and I understood people's frustration. However, some could've handled themselves more professionally, and that's the main point most people are trying to make. firewing628 never told people to shut up or to stop expressing their opinion, (nice straw man by the way) he's pointing out that there's a difference between criticism and complaining. Criticism is meant to help someone improve; complaining is just complaining.
Telling him he's bad for trying to be a nicer and more understanding person like the show teaches is shallow and definitely trying to silence him. If people want to vent their frustration, fine, that's perfectly acceptable! Just being a little more constructive about it is all we're asking.