As one of the Free People in game28 - I can say that noone on our
side has complained about him playing the Witchking - and I can't
imagine anyone will.
Anyone should be able to play. As long as it's not them entering the
turns there's no problem.
Actually I find it more likely that he will try real hard NOT to gain
anything remotely like an unfair advantage to avoid suspicions.
So leave it be (at least with regards to this game) - we will!
42 is the answer to life, the universe and everything!