(And yet another actor who claims to never have watched Star Trek...I don't know if that is a plus or minus as far as casting goes.)
It is entirely irrelevant as far as I'm concerned.
I suppose it is nice if they have seen Trek and are fans but really, all that is important is that someone is a good actor/actress, a professional and do whatever research is required for their job.
And neither should they be afraid to say they were not fans for fear of insulting or angering us.