@Gargron How about this for QuoteToots?
By default only posts with hashtags can be quoted (after all, they are intended to be fairly public).
Accounts can change to AlwaysAllow if they are, for instance, a news or campaign organisation or just want their Mastodon experience to be more public.
Accounts can change to AlwaysBlock if they are concerned about abuse or wish their Mastodon experience to be more intimate.