That's up to him, he could have charged a price from day one. But maybe he knew he preferred all that income from Patreon, so said, "i'll leave it as a free option on Itch, so no one can complain about how I care more about my Patreon customers, and barely care about my itch customers.
I want to know why you are such a big fan? Are you one of his Patreon customers, paying $5 a month for 10 months, so $50 with no update, but you don't care? To be honest, I find your attitude strange?!