I do not believe locking mechanisms in the overhead compartments are currently installed.
Controls to instantly lock/unlock such systems remotely by one attendant, thousands of times, reliably, is yet another challenge. Better to engineer a solution that requires no new equipment.
Engineering a solution that creates passenger conflict is not a good idea. I'd rather wait for slow people, than be around a loud argument at the end of a flight. I get enough stress already from hours of being cramped on a flight, I don't want more.
Also you are adding entirely unnecessary requirements to my solution. There is no need for the unlocking to be instant. Just to be doable one by one by someone going around the pace of people dragging luggage. The technology used for security tags in clothing stores would be more than adequate.
That said, I'm not seriously advocating for my solution. I'm just saying that it takes no more than 30 seconds to come up with something better than the one the blog post was about.