Turntimber Symbiosis put creature in play for opponent vs Oko

madwren

Playing in CotC today. 

My pw: Oko. 
Opponent: Oko.

I cast Turntimber, and it summoned out a Feasting Troll King on my opponent's side of the board. 

This was early in the game. His Oko did have a Fey Treat support on the board (Whenever a Food Token you control is destroyed or loses shield, fetch the first card from your opponent's library.)

I don't know why that would somehow interrupt and steal my creature, but it's the only theory I can come up with.  I've used Turntimber in other games and not had this problem.