That said, my speculations were about Google's intentions (not sigstore's) and if you think they are "completely untrue" then you are being misled and should potentially reevaluate the entire project.
Banning anonymous and pseudonymous contributors and requiring real names be provided to a trusted party is an explicitly stated goal of Google's[1] and one of the reasons they contribute to the sigstore project in the first place[2]. If I was going to try to make that happen, sigstore is a great way to lay down the infrastructure to implement something like that at a later point.
Additionally, anything that will centralize FOSS development (as being a root signing key for software would do) is probably not in it's best interests long term, because at that point the difference between a good and bad actor is a matter of policy and not a technical question.
I believe that you have the best of intentions, but others involved in the project clearly don't.
[1] https://security.googleblog.com/2021/02/know-prevent-fix-fra...