JO is signed for 2 years right? If that is the case he is not a tradeable asset this year; nobody would take him.
I wouldn't automatically dismiss JO's appeal.
The prior proposal was to move him for Hamilton on a 3-year deal. Saving another team money in the short term (which would be Nate expiring after this year) and the following year (when JO comes off the books) would certainly be something another team, Detroit in this case, would consider.
Throw in the possibility of next year's lockout and possibly not paying Nate & JO at all as opposed to knowing you've still got Hamilton on your books when the new CBA kicks in, acquiring JO can still act as a form of salary dump that may interest some teams.
One other bonus is that if JO doesn't get surgery this year, he can be possibly declared medically ineligible for next year, free a roster spot and possibly have his salary covered by insurance thereby saving the acquiring team some significant change.
I think it's premature to dismiss the possibility of moving JO (and possibly the necessity of moving him based on the recent developments to rehab another month so he can last the rest of the season and the playoffs)
EDIT: or to provide an example, think of what we gave up when we moved Raef to get Theo who had one less year on his contract