I can't get hung up about a twenty year old thigh squeeze either. Its a hair's breadth away from putting a hand on someone's knee.
Sorry what does that mean? Is putting a hand on someone's knee OK?
I don't think it matters if it happened 20 years ago or yesterday, 20 years ago was 1999 and sexual harassment had been a recognised phenomenon for at least 25 years. Men were already complaining then, that they didn't know how they were supposed to work with women if they couldn't just touch them on or near their genitals whenever they felt like it, or proposition them as part of their working day.
The decision to speak out about it now, may or may not be political, but the idea that just because it happened 20 years ago, it was OK then, is wrong. Men knew then, that squeezing a woman's thigh was defined as sexual harassment.
Also what's disturbing is that very few people have said they just can't imagine Boris Johnson doing something like that. No one's very surprised by the allegation. But as with Trump, it just doesn't seem to matter.