Anyone remember the news footage from a year or two ago, when a bunch of Humboldt squid washed ashore in La Jolla? People were picking up the squid and putting them back in water deep enough for the squid to swim. I watched those videos, and wondered if the people picking up the squid had ever paid attention to the Humboldt's biology and reputation. The squid have a lot of reports of aggression, and the tentacles don't just have the sucker disks - they have claws along their length. Even if the washed-ashore squid isn't being aggressive, if it decides to grab on in a defensive attitude, it can do some nasty damage to exposed or barely protected skin. Pick one up, and hold it where it could whip a tentacle around and grab me? No thank you. I don't particularly want to bet my skin on the squid remaining passive.
If nothing else, nature has demonstrated time and again that wild animals are not absolutely predictable. You could study thousands of examples of a particular species, and think you have a well-established pattern of behaviours, and then have one animal show up and do something completely different. (Wasn't that about what Cousteau said in his book about sharks? Every time they thought they had observed an absolute behaviour pattern, along would come a shark that would prove they weren't so dependable...)