Sorry, the line skipped. It was supposed to be, "What would he say to someone with a bit of gardening experience who told him that he could do your husband's job as a farmer better than your husband?"
The fact that it is on the lip is problematic. Many good dermatologists who would otherwise simply freeze off suspicious spots will not do that with the lip, because it is disfiguring to do so. I have a mole below my lower lip but right on the line (it's called the "vermillion line") of the lip, and my regular derm won't touch it. Anyway, if your husband really has cancer, please get him in to see whatever dermatologist will treat him. Get it through his head, he can die from untreated cancer, even skin cancer. (I have a friend who ignored a lesion on her arm, it was little, she didn't care, etc. etc. etc. despite the pleadings of her husband to get it checked, and yes, it was the most serious form of cancer, and yes, she did die, leaving her husband grieving.) Please tell your husband that some things can be burnt off and others can't, and must be cut out, and it does not mean the doctor is a quack or being excessive if one kind of spot needs light treatment and another needs more complicated handling. Does he want to die? You say he just wants to get rid of the problem, but he won't get rid of the problem if he won't listen to the doctors. How long did it take him to learn to be a farmer? What would he say to your husband's job as a farmer better than your husband? Well, your husband second-guessing what is necessary to treat skin cancer is about like that. He needs to listen to his doctor, whoever he picks.