First of all, please note that while I've been giving lots of feedback here, I'm not on the team that would make this decision. With my lang hat on, I'd like to see ways to get more testing of specific features; I don't know if this is the best way to do so, but it seems like a reasonable proposal to me. However, I think this would need to be, at a minimum, a decision made by release and possibly compiler and infra. Part of the issue here would be "whose decision is this".
Before writing an RFC, I would suggest reaching out to people on the release team, compiler team, and infra team, to discuss what team or teams would need to review and approve a decision like this. Once you have a clear story about who would review and approve such an RFC, then it may make sense to sketch an initial draft RFC that spells out the proposal, benefits, drawbacks, alternatives, and similar.