I’d imagine CS don’t have a leg to stand on, however nonetheless it’s far easier to comply with a DMCA request than worry about potential legal action
CS have really messed up and from checking a lot of places they’re already starting to feel the effects of it all
CS literally copied a planes interior and now they’re trying to stop creators (who, make no profit from these) make their own liveries. It’s stupid, selfish and plain dumb
Never buying a CS product again 
More to the point though, I doubt they can claim copyright over someone else’s work, whether it says it in terms or not; given CS hasn’t been given explicit written permission by a hypothetical creator to use the hypothetical work
Rip CS’s PR I guess