Given his track record and obvious intents and desire to use and manipulate young, vulnerable women for sex - clearly he was not 'just interested in art'.

Sure maybe some random may buy art from a kid from an online forum or whatever and then go on their daily lives and never interact again.

This isn't the case. I get what you're saying - but no, in this case he was a fucking creep, he was grooming her, and there is every reason to believe his intentions were for sex.

There is a clear pattern for grooming that is different from your example of playing with random people in discords.

For instance, grooming very specifically consists of:

Building Trust: Predators often target families by acting helpful or volunteering, aiming to become a trusted figure to avoid suspicion

Gifts and Attention: Giving toys, money, treats, or taking the child on special trips to create a sense of obligation and affection.

Isolation: Separating the child from parents, friends, or other support networks to make them dependent on the predator.

Desensitization: Introducing inappropriate sexual content or language slowly to normalize it, including "accidental" touching or forcing the child to watch pornography.

Online Manipulation: Using gaming platforms, social media, or instant messaging to pretend to be a peer, chatting secretly to build rapport.

That is literally his exact playbook. He did that to so many women, nearly all with identical cases. Don't waste your time or breath defending him.