I suggest you stick to neuroscience-related subjects, but you will have to really push.
The Hard Problem is a good place to start.
Also, when it comes to localising certain types of mental activity to particular parts of the brain - e.g. anger to the amygdala, ask him how anger can be localised anywhere, because anger is almost always about something - so it has to pull in all our other mental faculties. They have to realise there is something to be angry about before 'telling' the amygdala - so what does the amygdala do itself - other than maybe pumping out some hormones?
That argument seems to me to dismantle the whole notion that consciousness can be broken down into various simple interacting modules.
I'll bet T.E.S will have some great ideas, but
make sure he boils them down to something you definitely understand
Then of course there are NDE's. Make sure he has a bunch of information about NDE's ahead of time - then he can't argue that he hasn't read about them.
His politics sounds like it is rather poisonous, so maybe it would be best not to explore there?
David