I also agree in "innocent until proven guilty," because I've seen how people abuse others' good faith by making callout posts for petty reasons, or callouts that are outright false. In the end, those types of callouts just make it harder for actual victims to get support or have their legitimate concerns be taken seriously.
In Chris's case, I do think it's just as important that people at least be aware that the allegations against him aren't just over him being "an asshole" or "a showboater." I've seen discussions about his behavior for a few years now, so it's not anything that only started recently or is related only to FE3H/Smash.
https://amethystlashiec.tumblr.com/post/149095962046/regarding-chris-kirbopher-niosi/amp
I hope that if the claims are legitimate that the affected parties can do more than just make callouts on the internet. Unfortunately, like people on this thread have pointed out, it's very easy for the wrong people to use callout culture to their advantage. In the grand scheme of things, I personally don't think they accomplish much besides causing drama and confusion.
Edit: the thing about "at least he apologized and will hopefully improve himself" is that abusers will admit to wrongdoing if it will benefit them; it doesn't necessarily mean they are actually sorry. I do believe people deserve second chances to prove they've learned from past mistakes. But that requires more than just a calculated apology as damage control.