My first choice would be to give a Pro the spot because I'm just fishing and wouldn't want to interfere with someone trying to make a living. Now, if the guy was a knucklehead and pushed his way in or tossed some attitude my way then I wouldn't budge and would tell him why. It's simple respect and not everyone shows it or deserves it.
Heck, I have backed off spots for weekend tourny guys and received many thanks but again if the guy was stupid about it I wouldn't budge.