I agree with both of these points, users definitely need the ability to block instances that they don't want to see
Instances which violate your home instance's rules or are a threat to the instance should be defederated to protect the users on that instance and maintain a healthy community.
I know it probably wasn't intentional but I love what you did there "can be head somewhere else", I just think it's kind of funny because the malicous users are from the instance known as exploding-heads. I know I'm such a dork.