Presuming innocence doesn't make him actually, literally innocent. The reality of what happened is what it is, regardless of whether anybody can prove it to a legal standard.
Also, when you say "We tend to presume innocence", that's not really true. It's true (or is supposed to be true) for the government and people who want to be civically responsible, but a whole lot of the general population does not actually think this way. People think OJ did it, have various theories about who killed JFK, etc. People read the news about somebody accused of murder and think "yeah, that guy probably did it."
In your original comment, you suggest "misplaced anger against Facebook". Many people hold the belief that Facebook's products are harmful to children.
Following from that, I can imagine a few viewpoints:
0) Parents are wrong, Facebook is awesome!
1) Facebook has violated existing laws (these lawsuits are exploring that space).
2) Parents should be frustrated with legislators for failing to regulate social media.
3) Parents should be angry with themselves for allowing their children to use Facebook's products.
I'm curious which (if any) of these viewpoints you hold.
Not in the court of public opinion. People are allowed to judge guilt/innocence for themselves well in advance of being legally proven. Cynicism about modern day capitalism is thoroughly justified. The track record of ad-tech companies to "do the right thing" is really bad.
It's up to Meta to handle PR on such things. Unfortunately when your company is accused of, for instance, contributing to a genocide, your PR department probably doesn't have a lot of options.
