He looks like a nice colt to me. I think for you the question is more, "CAN we keep him?"
It's not easy to sell an unweaned colt unless you've got a buyer or two lined up.
Like all the other commenters mentioned, Arabians are no different than any other baby--they're all pretty darn cute but regardless, you can assess good structure and type even at this age. If he doesn't measure up to your other foals then I guess you would be correct in saying he's "average".
It all depends on how many other colts you have, how many foals you're expecting and whether you are in a position to allow him to grow up and mature?
Won't you kick yourself all over the arena if you sell him and five years from now he's become just the most gorgeous stallion you could imagine!
You either let time have her way, or you make a hard decision.
I'd like to see his sire and dam.
Thanks for sharing the pics!
P.S. You should never argue with a woman--young or old