Well.... if he wanted to use her to get famous in Japan, he could just... move to Japan.
What he never did.
And Ayu is a nobody out of East Asia, so, she could do nothing to help him in the USA.
Besides getting a ton of money (what I admit it's a good reason) is not like Ayu could have much use to his career. Like, at all.
But if he posted that meme about Ayu, and if this proves anything, IMO is that he liked her enough to get bitter and butthurt about the end of their marriage...