It DOES suck....but this guy is obviously just angry at life. You are obviously a compassionate person to take him out to his property 5-6 times. You mentioned he has dementia and is obsessed with getting rid of the honeysuckle. Just keep that in mind. He is one-track focused and it has nothing to do with you. You are doing a good thing...it sucks that he is not...but by retaliating you will not gain anything other than being like him. I say hunt it anyway.