Most of those booters are on their free tier, so it's a bit hard to argue it's a racket.

If you want to claim it's unethical... maybe. But if you think about it from their position, it could genuinely get into a slippery slope if you start policing what services you're reverse proxying. Especially considering the rate they're growing now.

Think of it this way: should Google be compelled to remove all search results for all booters and other malware-related services? It's asking a lot.