> they are privately owned and as such can make whatever deals they like.

Not really.

1) Meta is publicly traded, and has a duty to shareholders.

2) Antitrust laws limit what can Meta can do.

3) Paying individual executives to take action against Meta's interest is a crime.

4) A deal that involves Meta breaching contractual obligations with other parties or otherwise committing torts (e.g. libel) is also actionable.

There are more exceptions, but that should be enough.