Another way to look at it would be if he went to a fundraiser, and he ate a dinner.  If it was a $150 a plate dinner, you wouldn't want him paying the $150, because obviously most of that would be net going to the party.  But you also wouldn't want him to be eating for free.  So I think it would not only be OK, it would be preferred if he paid the party the $25 or so to cover their cost for the dinner.  That's what this sounds like.  And at the national convention, it really would be damn close to impossible to cover a single state's delegation if you didn't stay in the same hotel, because they spread people out over entire metro areas.  You're either in the same hotel, or you barely see people, especially since much of the action for that state delegation takes place in the conference halls of their hotel, and not at the main convention center.