It is In no way illegal to generate copyrighted material. It is illegal to sell that material. You're more than free to draw or other wise create any pic of bart Simpson you want.
There's a weird line here because I'm pretty sure the restriction is "commercial use" rather than outright selling. So even if they're including these AI products as "value-add" bundles or including them in i.e. Bing, they'd be tied the (ad, etc) revenue of the underlying product. There's also a difference between commercial entities and "personal use".
You might not be selling me a picture of Homer Simpson, but if you're providing it via a tool on a page with ads etc there's still a tie-in to a revenue stream and commercial activity