A male sex worker employed by a woman for sex would also be a rent boy.Rent boys has never been about the rouble. I can't quite tell if people are genuinely ignorant of the term or deliberately denying the term's homophobic nature. It has been a stock derogatory term since the 70s, fairly widely used in TV and film. Any dramatisation featuring Tory MPs in the last 40 years has had some allusion to the term - young, often vulnerable, male sex workers that are used by paying males (mainly Tories and rich men) for sex.
Think the link to Chelsea was probably the lifestyles in the Chelsea, Fulham, King's Road area in the late 60s and 70s. If it hadn't been insulting and offensive it wouldn't have become an enduring terrace chant and ridiculing one bunch of players for being mercenary would have had no staying power.
Nobody is ignorant of the term, it just isn't a homophobic one. It's sex workerist maybe.