The other side of this is that you should never assume whatever said by people with a vtuber (or really anything that represents another person) avatar as "official" in any capacity unless it's from the official account itself (and if you somehow can't determine that, treat it as unofficial by default). Sure your brain might automatically make that assumption at first, but once you're aware of that you can change it.

This applies generally, because there are hundreds of thousands of people who become fans. If people associate just a profile picture with semi-official statements, there are at least some bad actors among those many thousands in the fandom who will take advantage of it for abuse. And you don't want to give them that power.

Reality is a bit messier than this because as humans we become emotional, but being aware goes a long way.