That's one reasonable definition of hacking, but the examples he gives are trite. Changing a single letter on the sign of a school that no one has heard of is not interesting or notable. It's not even amusing. ("Customer Training College" to "Customer Draining College".)
He also contradicts that definition with:
I realized that if I could come up with a way [to eat with 6 chopsticks], it would be a hack. -- That train of thought is not playful, it's pretentious.
He had topped my hack. Was his action, too, a hack? I think so. Is he therefore a hacker? That depends on how much he likes to hack. -- So playful or not, if you're outdoing Richard Stallman, it's not hacking.