I can and did leg pump a swing around the top of a swing set.
I have to object the phrase "We don't think Titan will escape, because eventually the resonance locking process won't be able to operate, just as you can't pump your legs hard enough to swing around the top of the swing set,” said Fuller.
I had done it a dozens times when I was a child. No, not on a chain one. Here is a video of someone else did it.