There is no ReactJS company. There is a company behind ReactJS but that's irrelevant since there's also a company behind those millions of fake users.

What about my pet open source projects, shall I shut down their account because they don't have a company backing them?

I think you're arguing a point that no one upthread made. The proposal was to make sure that a real person was behind the account, in good faith - not necessarily that person's personal account. So your accounts and the ones you linked to upthread are fine. The "good faith" part means that there can't be a hard-and-fast rule for which Twitter accounts are okay. Human judgement will be required to sort out good-faith users (including brands or open source projects) from bad-faith users (paying people to run accounts that just inflate other accounts' numbers).