No, this is just an evasive way of saying you think it would be easy. And when people don't behave the way you think they should have, it's somehow suspicious in a way you want to have meaning in the real world. You have no idea what's easy, hard, or safe for a diver working in those conditions, so keep your uninformed opinions out of it.
How did he know it was a bullet hole?
No, "surely" is just another way for you to beg the question. What you think should be considered a factor in a forensic investigation is irrelevant because you have no pertinent knowledge, training, or experience. And once again, when things don't go the way you expect them, the right answer is not invariably that there is something wrong with those things.