Usually, I take a piece of rope instead, but the convenient one was covered with steel dust from the angle grinder, so
It was the ms201T and I used the stopper supplied by Stihl with the saw. Maybe not too bad.
It seems to go into the squish area, so the piston isn't far from the top dead center. That's effectively a concern, as the leverage on the crank and the connecting rod is as bad as it can be. It would be much more favorable at the halfway mark.
I did destroy a connecting rod on my 021 ( stupid cheap part, just stamped in a sheet of steel). I folded it in a U shape because I manly tried to unscrew the clutch the wrong way.
These work quite well ... plastic so no danger of damage ... used it to change the rim sprocket on the 395xp - might get a tad “deformed” especially if the nut is very tight (which it usually is) but can’t see where it can damage a piston or rod ... Remember it’s a left hand thread ... so you need to to go clockwise to loosen
Those I broke a piston with in a 200.
Had a 211 here, same thing. Many HVA and others that got cracked pistons from this as well.
I don't use any stopper any more. Rope trick is better but still risks...