Well, your wrong Dimz. When 1 person disagrees with you, you may have reason to argue, when two people you should then start having to be a little suspicious and then when a third comes in, you really should rethink your strategy.
The fact of the matter is, is that what Jigger is doing is to pay people for the creation of content such as code, graphics etc etc. The creation solely belongs to the creator, thus the creator is able to sell his/her creation to who ever he/she feels like. Epic doesn't own the creator work, they can't since they didn't participate in it's creation. Whether or not it goes into the actual creation of a mod doesn't really matter at all. What is illegal however is the creation of a mod that is designed to be sold/paid for illegitamately, i.e you can download my mod by paying x dollars to this account. Not legal. That is illegal since the engine itself was made by Epic thus the ownership belongs to Epic and thus the person does not have a right to sell it.
However, whether ethically/morally if this is correct is dependent on the person. Personally if I join a mod, I don't look for money. I look at what the mod can offer me in terms of challenging aspects and other such things, but not money. I don't often join teams that wish to further their mod by publications since that is usually seen as a big slap in the face to the community.
If you wanted to be 100% sure instead of just making beliefs, ask Epic if you feel like it, or in better respects consult the EULA of the Unreal Engine. But seeing how you post, it is mostly likely that you won't and will just call me an idiot. Well, it doesn't affect me one iota how big/right you think you are, but I have been down this road many times before, and judging by my 11 years spent in modding ... I've never seen Epic, iD, 3D Realms sue someone for selling his/her own work.