I mean, he's a self-employed artist, and one that has bills to pay. He set up a patreon to help subsidize his normal income (which is almost entirely commission-based, meaning it's not a particularly reliable one.)
I mean, I'm sure it's harmless in the long run, but it's kind of disrespectful to the guy drawing our fap material if you don't ask before posting his stuff for patrons. At least OP paid for the OP image himself.
The only time I've ever really saw it as okay to post patreon stuff was with one particular artist that actually emailed her content rather than posted it, and refused to send her older NSFW versions of her content when newer patrons asked (her logic was that this approach made people that were on the fence about her become patrons to get the stuff when they can, and when confronted with this, she literally said "Should have become a patron sooner.") That girl was an absolute cunt.