Due to an injury to my well-loved utility guy, I have to promote somebody from AAA.  I can promote a good glove bench guy who can't hit a lick or a fair bat 2B guy with a scraggly glove.  My AAA team has the best record in the league, my MLB team is kind of in the wild card hunt.  I could use the decent bat guy and he is in my plans next year.  Can I keep him up until right before the AAA playoffs begin and send him down, assuming I'm out of the WC hunt, without penalty?  About 25 games rmaining in the majors this season.

minor league playoffs don't mean crap

He can be returned to AAA without penalty when the BL returns from the DL.   Otherwise, you have to wait until roster expansion to call him up and end of the BL season to send him back down without risk of penalty.

Roster expansion has occured, 60-day DL.

Call him up and send him back down when the BL regular season ends.   You'll play the first round of AAA playoffs without him but I assume you're doing it for development purposes and not for the AAA championship.

Yep, thanks

The AAA playoffs can mean something. If you have players that are still developing in AAA, you might see another round of development on some of them if you make it to the league championship.  Doesn't happen all the time, but I've gotten a small increase on some players.