Actually this posses a question I want to ask any dev. "Am I able to print out a picture of Emi and iron it onto a tee-shirt I have for this upcoming convention, with maybe the KS logo on the back?"
I don't know, are you?
Jokes aside, sure, why not. It's not like we can stop you anyway, and if you're not selling them, no harm done.
If we go by the CC license, the answer would be yes as long as you don't make money out of it.
Strictly speaking, the CC license only applies to the game distribution as an unmodified file (and it in fact states it can't be modified or derived from). Anything not covered or not specifically allowed by the license is covered by the same automatic copyright that applies to pretty much any creative work that does not come with a specific license, which means you're pretty much allowed nothing except consuming/using it - plus possibly claiming fair use depending on your jurisdiction, but that is such a vast topic I won't even start.
Making a T-Shirt for your personal use using game assets is nothing that would make us frown though, unless you come up with a horrible design and pretend it's official.