Watching JJ Riddick develop into the player he has gives me hope that Jimmer could develop into a contributor to a team. Seems like a low risk, high reward scenario at this point. Let him run with the 2's and get some experience. You know he'll go off at some point if he's playing in SLC in front of fans that have named their kids after him. As the OP noted, he's lost the Jimmer swagger and he could get that back on the Jazz easier than anywhere else..
I don't see the downside for the Jazz..