My point is similar to Chris's, actually.
First of all, I think if we're going to list all of those witnesses other than ministers, who cannot be compelled to attend a committee, we should have that football player on the list as well.
But I don't think we can issue a summons until they've been invited, or maybe the term is “called”, to appear. Until they're invited and turn the invitation down, then a quite complicated process begins to actually issue a summons and compel their attendance. I think the most we can do is to call these witnesses to the committee and see if they cooperate. If they don't, then they're in contempt and a summons can ultimately be issued, I suppose.