"The Laconia had come into Plymouth the week before; no danger of her being sent to sea again. "

Given the circumstances of the death of a close friend's fiancee - a fellow sailor no less - and the fact that his ship was not leaving, I can't imagine CW's superiors would have denied his leave.

I don't think CW really risked much professionally either. It's not like he was running out on active duty - or that his superiors did not know where to find him. He was on the Grappler - another Navy vessel.