It gets rid of the “these would be gone under biden argument (this is what they are going for, like a toddler in timeout)”, and as the secret poll Don Lemon and others at CNN implied, people seem to be against the protests that get violent. They will likely stop pushing it as well, and/or blame The “far right” or some other way to make Trump responsible. It also shows he condemns the violence, since if Biden can disavow, he can too.