This is so disingenuous. HC started and managed several of the biggest OSS projects out there. They significantly contributed to and evangelized OSS for over a decade. It's easy to say "we don't need their support" when you're piggybacking off of 13 years of their work and money.
I think that's what frustrates me about this whole thing. It's not the actual forking of terraform but it's the attitude that the companies and people behind OpenTF have had as they've gone through this. There's been a certain smugness and sense of entitlement that this entire thing gives off which doesn't sit right with me. Don't forget that the main drivers behind this are companies that stand to lose the most (commercially) from the licensing change. It's not as altruistic as they make it seem.
I would probably feel better about it if they just came out and said that this impacts their business prospects and as a result they're forking it. But they put this "we're doing this for the community" veil over it which feels disingenuous.