It's a shame when something like that happens (thompson)... but, this is not you, it's someone else's issue
Looks like people still have issues with intimate waxing and therapists, being them male or female... I'm the only one in milion people city that does male brazillians... but that needed soooo much text on my web site and soo much talking on the phone and soo much talking when they actually come here...
... I am always very strict about underlining that intimate, or any other waxing is a service, and just that, and that for me that is only hair and skin, and that it's all it should be, hair and skin!
So I think the male therapist should point out - and ask if the feel comfortable about it - I'm a male, I'm a professional, I'm doing that service... my God, and what about male gynecologists? I bet women don't have that kind of issue with them!
With new clients (intimate m/f, or first time males) I always say - I know it's uncomfortable being naked, or almost naked, it's uncomfortable to lie down and have someone touching you places. Especially because he is boy and I'm a girl. While I'm waxing, I'm not a girl, I'm a person who removes your hair. You're not a naked boy who 'presented me with his stuff', you are a person having that service done. I will have to touch you places, intimate places. But I have to, to perform the service. So I'm touching the skin, not 'your bits'. If you are not comfortable with that, then I don't have to do it against your will and comfort...
If they get erection, and apologize, I say - that's perfectly natural, because it's all adrenaline and nervousnes, and people react in different ways. If they say nothing, I don't say anything either. And always am comfortable saying names of the intimate parts... without saying hmrm.. urgh or so.
And never have someone else during the service. Why? Is someone affraid? Of what? If so, they shouldn't go there! If they feel that being a man implies that he cannot control himself if seeing bikini line, or what? I'm looking at male bits all day long and to be honest, I don't give a damn, I'm not imagining things about them! They are clients with hair and skin to take care of.
If I'm comfortable, they will be too. At least, in your countries you have consent forms they can sign and you can wash your hands of any guessing afterwards...