If anyone -- attractive man, unattractive man, attractive woman, unattractive woman -- started hula-hooping in the middle of the office I would expect people to stare. Not because it's sexual, but because it's peculiar. The gap between "stare" and "ogle" is hardly objective, let alone a "chasm."
The hard part here is defining "lecherous" but it would seem to imply that he is watching in a way that signals sexual intent. It's worth noting that women are generally much better at interpreting body language than men are, so it's possible that a guy is watching the woman dance and getting some sort of erotic enjoyment from it, tries his best to hide it but some subconscious subtle clue gives him away.
Having said that, hoop dancing would seem like an inappropriate thing to do in most offices to begin with but I would say the same thing about nerf gun fights.
Anyway, another account of the incident paints a very different picture of the scene:
https://news.ycombinator.com/item?id=7408466
claiming that the gawking in question was undertaken by all present and not limited to men