Newbies don’t know what they don’t know. Literally. I doubt he knew either that his boat was vulnerable to capsize in such conditions, or that he had no means of timely recovery if it happened.
I am not saying that he could not have found out - there is at least one serious kayaking place up in Wickford that would have tried to get him set in the right direction. But people active on this board tend to underestimate how far off the assumptions of a newer or untrained paddler can be. Especially so for those who had that initial not-smart experience and lived to learn better. I can be pretty thick. It took two of them to properly get my attention.
A relative had an Old Town Otter that is likely under the water in Muscongus Bay forming its own little home for critters. She and her husband sincerely thought that if you left a boat upside down it could not float away, even with a high tide overnight that came in at a plus 1.5. So it wasn’t tied down…
There are two college degrees involved here so it isn’t about measured intelligence. My guess is that it was a combination of the husband’s penchant for unfounded grandiose statements and their being in vacation (drinking) mode. But even with that, it is a choice that will leave most on this board scratching their heads.