Well, it seems like when confronted with detailed arguments, they ignore it, and try to make it appear as if they never saw it.
If you only say, "oh Deuteronomy speaks of an Israelite prophet", then they will argue, because you have not done much more than pronounce a statement. But when you show in detail how their argument fails, then they ignore it until they think no one remembers it... then they come back again with it.
I have posted this in several forums, and I have had no response whatsoever. I have also posted the one on the Parakletos, and no one is willing to talk, except in the Shiachat forum, but even there, the person did not even read the whole work, and started arguing a different point.
But that is the nature, just read that post by H20, urging other Muslims to not respond.