VIP yes or no
You are correct that is illegal and hypocritical. I don’t think it’s so much a legal or STI matter, I think many WG’s simply don’t want to suck a man’s dick raw, they might find the smell, size, or precum /cum in their mouth nasty, whereas getting paid to lie down and spread her legs doesn’t seem like such a bad deal.
That said, it would be less offensive to a client to explain it away as being unsanitary and illegal rather than uninterested in sucking their junk without rubber.