Julian steps forward fearlessly--he's cautious, but that and fear are not at all the same thing--to check the man's vitals, and then satisfied that he's not severely injured, passes him off to his friends to get to Sickbay.

"It wasn't an idle offer when I said I could treat your injuries," he says--explanation for why he stayed. There were more than enough doctors here, Doctor Crusher, Trance, Simon, or McCoy could see to the knocked out Ensign. He wasn't willing to let this man out of his sight--not that he was Security, but he was certainly curious.