Any guidance on the laws referring to refusing to treat a patient in a snf? Massachusetts

Year long story short a male in his 60s who moves from nursing home to nursing home due to behavioral problems has a very limited number of nursing staff members that can work with him because of his list of allegations against them. He also blames therapy for his latest GI hernia (his 3rd but first in facility). Very accusatory, racist, verbally harasses, thrown food and has been aggressive but never made physical contact. He’s been discharged from therapy for months but is demanding therapy despite being at baseline. Knowing my company they’ll find any reason to pick him up. So at what point can I refuse to work with him? Do I have to wait to be physically assaulted before I can say no? Seems wrong. He also has threatened everyone’s license several times. The man has no evidence to stand on just a miserable person. So any references or guidance on practicing with this kind of population is appreciated