what elements were created in photoshop? it looks like the flowers are a masked object, as with the table shadow.
the issues I can see with this are:
1. the flowers look like they are made of playdough
2. the shadow doesnt look right ( looks like it was made in photoshop). the talbe legs should be casting shadow.
3. the vase isnt shaded at all, and has a very blurry texture.
3. the doily under the vase has blue behind it.
4. tha table has no texture, and the legs are wrong
5. no floor definition.
it seems that his has the same problems as your previous work.
I'm not an attorney, but based solely on what you've written, he most definitely does not own the rights just because he's used your work and not paid you. I mean, that's one of the stupidest arguments...