The terms of service explicitly say that art remains copyright of the artist. Where are you reading that suggests that they’ve granted themselves extra rights?
I guess you could interpret “are the property of Cara and/or the individual artist” to mean “are the property of either Cara and/or the individual artist at Cara’s discretion”, but that’s such a stretch that I can’t see a judge accepting it.
Oh, hah. For some reason I assumed that the point of the comic was that the aliens heard “run for your life” and took that literally, thus moving to a pedestrian healthy city or something.