To answer your DSD question as simple as possible: if he was following DSD standards, the instructor should have been with your son (i.e. less than arm's length) the entire time your son was in the water. That means the instructor should have been right next to your son as your son ascended the ladder onto the boat, where presumably another crew member could assist your son with his gear.
Sounds like the instructor left a little too early, and he figured it was no big deal because everything turned out ok. He probably does this all the time, and so far everything has turned out ok.
There was a very lengthy discussion about this in the A&I forum a little while ago... minor violations of DSD standards are regularly brushed off by instructors because "everything turned out ok." Essentially, they violate standards until that one time things don't turn out ok (which is why the discussion was in the A&I forum.)
Sounds like the instructor left a little too early, and he figured it was no big deal because everything turned out ok. He probably does this all the time, and so far everything has turned out ok.
There was a very lengthy discussion about this in the A&I forum a little while ago... minor violations of DSD standards are regularly brushed off by instructors because "everything turned out ok." Essentially, they violate standards until that one time things don't turn out ok (which is why the discussion was in the A&I forum.)