In my non-U.S. hometown (people in the U.S. are, on average, much more shy in this context, oddly enough), this would have been considered extremely rude and aw

In my non-U.S. hometown (people in the U.S. are, on average, much more shy in this context, oddly enough), this would have been considered extremely rude and awkward, and the boss would have been made fun of forever. And not because he was in shorts, T-shirt and sandals, a respectable attire at the beach or pool, but not when other people are striving to present themselves at their best. Putting people down should never be fashionable.