Bug in Tahm Kench...?

I didn't know the place where people can report in game errors so I decided to do this since it has a "report a bug" board.

Now this took place in a bot game, but the issue is still there.

I was playing as support. Now about mid way through the game gnar had been hard engaged on... he was almost dead so i used Devour to save his life. Now according the ability, it places the target champion or minion into stasis. "Stasis" for League says:

The target is unable to control movement, attack, cast abilities, activate items or use summoner spells.

• The target is also untargetable and invulnerable for the duration.

http://leagueoflegends.wikia.com/wiki/Stasis#Stasis

Now ended up dying while inside of 's belly. He said that he was ignited and I know that Bot was ulting at the same time. In any case he should have been safe since he was supposed to be invulnerable during the duration of Devour.