Exactly! Possibly with an automatic rifle you find in abundance in these MODs to emphasize your point. Or how you see it on these excellent series:
I think that doing so would result in you being imprisoned. Or gunned down.
Demanding something, you gave for free, back is robbery. Giving is transferral of ownership, now they own it.
The reason Hobbes situation is somewhat different is, that his modpack is intelectual property, not a physical object. He never gave away the right to his modpack , he merely allowed others to copy it.
And even then, unless he intends to use it for gain himself, I think it was a poor move. I do not mean the licence declaration. I mean enforcing said licence on things based on previous versions of the modpack.
Sorry, buddy, I couldn't give a fig about what you are doubting. I stated facts. Also if I decided to be in the place of Hobbes I would go after every SoB using my content with LAWYERS giving immediate takedown notices or suffer being sued to bankruptcy. No mercy!! 
How ironic.
Also, if at least one person challenged you on that, you would likely fail. The whole modding thing is a legal gray zone. Add in the fact that hobbes allowed usage of his assets before and you have a whole mess.
Basicaly, if you were in his place, you would have to prove 3 things
A) You are the author of the assets (Somewhat iffy. Many of the tiles were recolored TFTD tiles.)
B) The assets used are the same ones (Easy. Hobbes was credited.)
C) The usage was not allowed at the time it was done. (Impossible. It clearly was allowed until the declaration. Anything posted before it would not be affected by it.)
And let's not forget that winning this lawsuit would make you easy target for whoever now owns Microprose, because of point A. Microprose has an actual licence on X-COM.
