To be fair, ActivityPub is an open standard, so corporate adoption was a guarantee following any amount of success.

As an advocate for ActivityPub, I want to see more entities using it. The fact that Threads and Flipboard will interoperate will likely convince more corporate actors to join the fediverse, and I don't think that's a bad thing.

There will always be instances that block out the entire corporate fediverse, and those communities will still thrive alongside instances that do federate with the corporations. People will have freedom of choice without having to exist in a bubble, and I think that's great.

The strength is in defederation, where communities can decide who they want to play with. I'm not personally worried about big companies like Meta embracing ActivityPub because their bad behavior will have consequences for them, and the community is starting off vigilant and aware. If they play nice, the community might loosen its grip, but if they act exploitive or abusive, they'll get shut out from most of the community forever.