Re: Security or Marines?
Well all I can say is that they knew they were McCoys freinds and they knew Kirks mavorick personality.
No doubt they may have been warned before hand to keep a eye out on them if they turned up.
I think that's a stretch. Kirk had no maverick personality until the events in question. It was only after TSFS that his reputation as a rule-breaker came to light. Before that, he'd been a respected member of Starfleet, albeit something of a dinosaur.
"I've sworn an oath to serve and protect the United Federation of Planets- an oath I will fulfill with my dying breath- for in my heart, I remain a creature of duty. I am Romulan." --Captain Sran, USS Naptown