Not sure it's silly at all, at least financially. To know that we need to know how much he would get to stay for next year.
2nd round exception deals are 3 or 4 years, with the last year being a team option, and AAV between $2-2.5 million. Odds are he's not getting that much to stay next season, but if any of the insiders want to confirm one way or the other I'd be interested to know. Plus if he sticks in the league, he'd get to NBA free agency one year sooner, which is where the real money is at.
The only scenarios where coming back is a better financial decision if he gets that 2nd round exception guarantee are, (1) if we are paying him more than the 2nd round exception he'd get AND coming back won't hurt his draft stock (can't guarantee that) or (2) if if he improves his stock enough to get picked in the first round (could happen, but also not a guarantee by any means and being a year older is always a strike against you as well).