@dzaporozhets How much effort do you estimate it will take to find all places that touch MR rebase and add project.feature_available?(:merge_request_rebase) checks to them (both on frontend and backend), so that this feature can be turned off for a specific project in its entirety by having that method return false?
Project#merge_method is EE-only and looks up the projects.merge_requests_rebase_enabled column to determine whether it should offer the rebase_merge strategy.
The brief is to have EE act like CE when a project feature isn't available. Currently, we provide a "rebase before merge" strategy that is in neither of CE or EE.
I'll create a follow-up MR to resolve this by removing the strategy entirely.