Don't worry about breaking flow, we don't need to put up with risky hygiene unless we're being paid specifically to swallow pee, smegma or poo. I'd cover, refuse offer HR, or walk if he objects. I don't want to re-book clients like this. After a lot of embarassment and squirming I'm now blunt and tell them they smell.
Alternative strategies-I've send them back, and they're so apologetic. I had 3 in one room and made 2 wash their dicks..no arguments or bad feeling, doesn't put them off. Doesn't matter if he's in yours, a hotel or his home-be calm, firm, control him. If I want to save time and expect another client I will sometimes soap them up with a hot flannel, the're fine with that. If it's a longer expensive job I'll get in the shower and wash them inside out, they love the special VIP treatment!
They're paying ££ per minute for breaking the flow because it all comes out of their time not mine, that clock's ticking while they potter about working out how to use the soap.