[Gameplay] Tahm Kench can eat anything... but metal!

While in a One for All game, my team picked Tahm Kench (or rather we were blessed with the beautiful opportunity to eat each other O.o). Lo and behold, I was up against The Dongerdinger ... Sweet... (Why is he not disabled along with teemo???)

Picks and result aside (we won), I noticed that if I used Tahm's W on a Donger turret, the turret would sometimes be immediately ejected from Tahm's tummy, and would become invincible to damage after reaching 1 health (much like a Tryndamere ultimate). The turret would eventually disappear after it's timer ran out, but my minions would still spend a good 5 seconds smacking the turret to no avail.

Has anyone else had this issue? I know The Donger isn't a popular pick, along with Tahm Kench, which may be why this bug hasn't been noticed yet.