What's the first thing you do, after you put a bed together? Jump on it, to see how comfy it is.
Years ago, I asked a guy to help me to put up my new bed. After it was up, we shagged on it. Both single at the time, so no issues there. But come on...the innuendo is obvious!
He's being spectacularly stupid if he helps her with this. She's already made her intent obvious, with the texting and the feeling of his bum. If she does make a play for him in the bedroom, and he rejects her, she could turn really nasty and tell a completely different story to colleagues or HR. And if he said that he had never encouraged her, the stock reply would be "You were alone in her bedroom, clearly something has been going on between you".
And you might think that no woman would be that nasty? I've seen it happen twice.
Oh, and I just remembered about when my Ex best friend was single, she kept asking the married neighbour to help her with "jobs". Even stupid stuff, like putting up a picture (can't everyone manage that?). Turns out they were shagging every time.
Anyway, your question was, what would I do? My 20 year old self, would have done nothing, except hand wring and worry. Now (at 49), I'd contact her directly, and tell her to back the Fuck off. I just wouldn't stand for this absolute piss take. No way.