Okay, then I think we largely agree. I'll concede it probably happens for more than a "day or two", but again, if a guy has been out for any length of time, he'll need a rehab to be ready to play when he's brought back, and once you start that, the clock starts to tick.
Really, I don't care that there's no limit on how long you have to activate a guy, I just think it would make sense to implement logic similar to what they have for veterans in ST. You can leave the guy on the DL as long as you want once he's healthy, but you run the risk of him regressing.