As a middle aged whiteboi your father is from a less enlightened pre-BNWO era. whitebois his age saw far fewer Black people and were more able to suppress their inherent whiteboi desire to submit to Black Men. The submission craving has always existed in the whiteboi psyche of course, but historically whitebois have suppressed it with overt racism.
However your father now lives in a time when IR relations are thrust in our faces from every medium, Blackness is celebrated and white males are denigrated and humiliated. We younger whites have a headstart on Black worship, but the Overton Window shift affects older whitebois too.
I suspect that he is weakening to his inherent submissive nature. By going Black Only you have greatly increased his humiliation and whiteboi submission thrives on humiliation. You can further his humiliation by insulting whiteboi inferiority often and very casually. I would suggest you help him see DarkWanderer and make sure he is well aware of the eager white sissies here.