Note that the documentation clearly says that --nameserver expects an ip address. Now we could make it accept a port too, but that would not make the OP happy, as he wants to talk to localhost, but in tor mode, all dns requests are routed through tor (this is actually one of the main motivations for using a custom DNS resolver).

Agreed, i think the OP is asking for X when he wants Y, so that makes this request a little bit strange.

Still, being able to specify a port (or at least have it clearly documented that it's not possible to set a port) would be useful.