Probably isn't mileena specific
Any move with that many frames of hit stun (or a move cancel able into another move) will probably produce this same effect.
The problem would probably be forcing the trade with flame aura.
I'm pretty sure this is the case. I use a handful of characters (yes I know others beside Mileena lol), but nothing really comes to mind for creating this trade. Maybe Cassie's nutpunch could let her combo off, or D'Vorah's F1.
Mileena isn't recovering faster, I don't think, it's just that she recovers first, and the cancel window seems to still be open but it's letting her use a normal instead since she's grounded instead of in the air for an air sai cancel. If you look at how long you can delay an air sai on hit, it seems around the right time.
Imo, it's a fair trade only because this only happens on specific frames when both telekick and aura go at it. In a lot of cases, telekick will just get beat out and Mileena eats a combo. In the MU itself, unless aura is done right in your face, you can't even punish it or check him, so there's that too. Like it's such a specific scenario, kinda like 6 acid spits in the corner with Acidic and then landing your optimal bnb for over 60% lol, that it IS just dirt at the end of the day. Just my two cents