The easy solution is Seismic Grenade and AOE Sleep / CC.
In your case, the one who get opened by 2 infiltration Sin need his teamate to throw that grenade so the both Sin are stun. That give enough time to dot them and kite them as well.
There is a lot of counter stealth mechanic in this game like the sniper getting high stealth detection when covered, Stealth detection on Bounty hunter / Trooper. Spamming AOE (Force quake / Lightning Storm) etc.
The theory and the reality are often to different things. Only time will tell us.