Bigotry certainly stifles good debate.
Consider that debate is a means to learning. If you are bigoted, you hold fast to your own viewpoints and refuse to consider others, regardless of how compelling they are. If that's the case, any debate, discussion or argument a bigot engages in will likely be extremely limited in scope, lacking critical thinking and is self-serving rather than seeking truth or understanding.
I still maintain that by and large bigotry is called out before it has a chance to 'stifle' anyone, bigots are a minority and those that are stifled by bigotry are an even smaller minuscule minority.
So ok then yes it does but to the point where it is questionable whether or not it merits discussion.