It is true that you have to be very wary of giving tochacha. Especially nowadays when few people know how to give tochacha and few know how to accept it.
So you are right about that, ZD. However, the issue is not about whether or not you will lose your job (as Time pointed out). That is self-centered. The issue is what is the most effective way to influence this particular person. That is the issue of concern here. And in most cases of alternative lifestyles, tochacha is unlikely to be very helpful.
If it does come up in a conversation (brought up by him, not you), you should not be afraid or embarrassed to acknowledge (firmly yet kindly) the Torah’s position on the topic, while being sympathetic to his situation.