Having a Facebook account is a symbolic/emotional injury to a tech contrarian, but I don’t see the courts particularly caring about that. It’s not like you have to actually spend any time or money on it.

Is that actually a criteria in antitrust?

Antitrust could care if other social networks were unfairly disadvantaged because everyone was using the Facebook account that came with their Oculus.

Having an entry in Facebook’s users table is a long way from using Facebook for your social networking to the exclusion of competitors.