Thank you for your reply. No, I think I will just eat the $10 loss and consider it a lesson learned. It's just grating that I specifically asked this developer where I should buy the game in order for him to get the best cut, and he said that would be itch, so that's what I did. Had I done what I normally do and just bought it on Steam, I'd be able to play the game whenever I like.
I appreciate you discourage creators from doing this, but the very fact that it's possible leaves a bad taste in my mouth and I don't think I'll buy any more games from itch. No hard feelings; I wish you all the best.