I'm thinking in a new proposal to add to your 3 points:
Introduce negative delegations.
Suppose that you don't like bidbots. Then instead of creating a bot to flag all posts voted by them, you give a negative delegation, meaning that their vote value will be reduced a little bit.
So, it is like a flag, but in a big level. In this case, you don't want to support all the actions of a specific community or user, similar to when nations put sanctions or fines.
The point to discuss is the level of subsidy of these negative delegations.
Only a "money miss road" will do that. Since he or she won't care about ROI. We don't call people like that Good Samaritans. They're called idiots.
I was thinking in something like this but for delegations.
I mean, with the flags are the same, you don't get curation rewards by flagging and this is the reason @kevinwong is proposing subsidy downvotes. You can do the same for negative delegations.