Is the sky blue? This is why the fediverse exists.

Although it would be jumping the gun a bit too soon, you have to let them incriminate themselves. Give them a few weeks and enjoy watching them wasting their time trying to appear to be good faith participants. Then clamp down on them hard when the inevitable hate starts spewing out. Be quite upfront about what you are doing, in fact warn them and their users they will likely be defederated in the future due to the expected devolution of discourse from anyone identifying themselves as such.