If one single sponsor does not agree with their sponsorship being transferred, then that is THEFT. There's just no way of excusing that.

On the other hand, even if an overwhelming majority were okay with sponsoring the fork instead, cancelling their sponsorship and emailing them about the reason and how they can sponsor the new project (or continue sponsoring the old one, if for whatever reason they'd want that), then that's a minor inconvenience.

Is it really such a hot take that erring on the side of minor inconvenience is better than accepting outright theft based solely on the perception that most™ users will be okay with it?