If a question has been closed because it is likely to lead to heated or extended discussion, is it right that a single answer presenting the bias of the first person to respond be allowed to remain?
When a question is closed, the answers to it are generally considered separately; they are not automatically closed at all.
Though if the question gets deleted, the answers of course are deleted, too. If the question is that bad of a flame generator, that's likely going to happen.
The question might be reopened, as a general rule (not speaking to the specific case, which you have not linked). So generally, if the answer does not offend on its own then yes, it should be allowed to remain unless the question is deleted.