A better solution is to let Kind 5 events delete pubkeys and have relays handle it. I’ve been meaning to propose it.
I’ve already created a small server that does this, although it needs to be self-hosted. Can handle thousands of keys easily: https://gitlab.com/soapbox-pub/plan-b
Discussion
I submitted a NIP to deal with this. Take a look please #[0]
not a great solution, better to use multiple keys