@danmaruschak had a good idea that rewards could go via an exchange and then they'll be completely anonymised - the downside is it would have to be done manually.

That is a good idea, although the need for manual processing basically means that it can't scale. I think it's possible to code bots to work with the exchanges, but I have no idea how difficult it would be. It's almost definitely not a short-term thing.

I had a similar thought in the past, that exchanges could set up staking and anonymized delegation services, which could be used by abuse fighters to disguise the source of their delegations.

The use of exchanges hadn't occurred to me in this context, though.