you gotta admit that move was cool

@Background Pony #D138  
Aside from what FanOfMostEverything put forth, it could be that he has enough control of his magic to discriminate against affecting certain targets, assuming this is a magical sort of effect, which considering Tirek can channel magic through his fists ala “Twilight vs him in S4” and him vs the Pillars (albeit that time with a foot), wouldn’t be at all shocking, along with the fact that Tirek is one of the most skilled villains with magic, with the only ones rivalling him in the regard of finesse being Discord, Sombra, and Nightmare Moon.
 

 
Starlight (herself a villain at one point) demonstrated a similar thing in To Where and Back Again, where she didn’t repel Trixie.

Blow them away all you want villains, but Equestria will keep coming back.

@Background Pony #D138  
Why would you ask that question? Nobody cares. Get over it.

@Background Pony #D138  
She’d turned into an alicorn, dude. Think about how crazy strong even Flurry is.

@FanOfMostEverything  
About Chrysalis I could believe it, not so much for Cozy, considering her size.

@Background Pony #D138  
They may have been strong enough to power through it.

How come that shock wave didn’t hit Chrysalis and Cozy when stading right next to Tirek? Friendly-fire was set to off?

Go away every creature!