Especially not simply making the site not load like that. If you really think a browser is so bad you don't want people using it, at least have it redirect to a message explaining what your grievance is. Unless the browser is DDoSing webpages it loads successfully, making the site look broken is pretty worthless as a response.
EDIT: Although, it looks like they tried to do that sometimes? No idea why they would switch from that approach.
EDIT: Although, it looks like they tried to do that sometimes? No idea why they would switch from that approach.