IBTZ! No liberals allowed!
IBTZ does not help in that regard.
If he's just trolling, he will make himself known and the Kitties can have their way with him. If he's here out of curiosity and an earnest desire to understand, then engagement would be the proper course of action.
It wouldn't hurt to have a self professed liberal academic a little more open to conservative points of view, now would it?
Besides, if he truly does support the 2nd, he can't be all bad. And probably not as liberal as he might think.