Lol, you guys.
They buffed penals to make them more useful, this requires SOME kind of improvement.
As Katitof already said, "its most expensive early game infantry, coming from least flexible tier. Rather obvious it will serve 250-240mp generalist inf good when it costs 300 itself and is AI specialist"
Your analysis completely ignores other units like cons and combat engineers which have not been buffed at all. This is because SU needs a unit to take the 'frontline infantry' role, this is the penal squad. I.e. you're looking at penals in isolation and trying to claim that they alone are OP, but maybe you were being hit by a mortar or maxin or a mine while the penal was attacking? How do we know you're being completely transparent in your post?
P.S. plenty of units can wreck squads on retreat: these incl sturms, 222, T70, obers, storms, commandos, rifleman BARs, snipers, assault grens, 42 grens...
You need to incorporate those units into ANY argument you make about units being killed on retreat.