Specifically, tenure is to remove the pressure that "you'd better be right" so professors are free to take meandering tangents through the solution space that don't seem like they'll pay off immediately.

The failure mode of tenure is that the professor just rests on their past accomplishments and doesn't do anything. That's a risk the system takes. In this case though, Geoff Hinton is doing everything right: he's not only not sitting around doing nothing, he's actively trying to obsolete the paradigm he helped usher in, just in case there is a better option out there. I think that's admirable