Wow. That's a challenge to be sure. Most caregivers would refuse to take care of someone that makes them that uncomfortable. But, you need to ask yourself some things:
Can this fellow manage alone? Obviously not.
Why is he acting this way? While you are not a psyche nurse, you can understand that there is a reason for every kind of behavior. If he is terminal, there is darn little he still has control over.
That being said, he may feel helpless on the inside, and his masculinity is also being affected. He may wonder if he is still desirable. An honest and o.k. question for him to ask to himself, if that is the case. And those needs don't disappear with a terminal illness necessarily.
That does not excuse his behavior, but it may help you to understand it.
First, if you are able, you need to set limits and it's ok to do that, and chart those limits as well, and have the nurse put it on the Care Plan.
If he is able to handle a washcloth, he can clean that area himself. If he wants you to inspect the area, you can ask him to show you himself, without you touching that area at all. If he continues, you can tell him that due to the suggestive nature of his conversation, you are compelled not to return and need to report it then do so. Document, document document.
If he gets upset, let him. But stay calm, direct and respectful.
He may get a notice from your company informing him that in __days your company will no longer be providing services.
Keep your office informed!! Just some suggestions.....