As it could be considered " activism"( boy they love that word don't they?) Contributing For a first book, given the time it's requires and that it's adding to the pressure on the cult, OK.
But I wouldn't contribute to a second as now you are just his employer without the perks of being one. I don't know other authors who are paid by random strangers, not their publisher, to write their books....go on booktours all over the world like some celebrity after selling 2000 books.
I doubt people who have written far more worthy and seminal books have had the same level of support.
He, and you, have done their bit for society, now it's just furthering his career.