Not just a bully; you could argue that this is sexual harassment.

The senior deserves to be called out and lose his job, which I hope the OP follows through on. I've worked in toxic offices like that, with people who turned up too late to even scrape the bottom of the morality barrel. Never again.

I wonder how many other people there have stories of him being a vulgar bawbag, and how much HR / his boss knows.

OP should be looking for new employment regardless; if there's one of those chucklefucks in a senior role, it's safe to say it's management-endorsed and that the company is probably rotten from the top down.