The problem here isn't talking to Meta or Meta making a federated platform.
Nobody can prevent Meta from doing that anyway.
The problem is the need to push against the insistence of Meta to keep these meetings off the record. It's against the entire philosophy of something like not only fediverse but FOSS in general.
If Meta wants good faith, they have to show it first.
Notice that in the email, Kev gives his guidance as to the matter. Do whatever the fuck you want as long as you put people first and make a product for the purpose of serving them.
This should be the attitude everyone should have first.
We will accept you as long as you're bringing value to us, not the other way round, got that Meta?
As long as any dev is taking this approach, Meta included, I'm supporting them. If someone is secretive about their intentions about a public service which is not a for profit endeavor inherently, I'll have a hard pass too.