Okay, I expected that one. "Can't be bad - I protect my outpost and make some space for the queen", he added.
Since then, I have always distrusted the Zilbermints gambit. Maybe it is me being an engineer, wanting a clear path ahead for every move, that narrows my eyesight, but I cant see any white plan here.
Let's consider 10.Qe1 (what else) followed by the simple exchnage 10...Nxf3 11.Rxf3 (diagram). Note that black has stronger 10th moves and that taking the knight is rather silly now, aftre having defended it first with c5, but anyway.
My silicon assistant now gives 3 moves that give the defender the advantage : 11...Bd7, 11...a6 and 11...h6. Of course, white can only dream of black castling now into it, but that is not real chess, but wishfullthinking chess.
Let's consider 11...Bd7. Houdini suggests 12.Rad1 (diagram) - who am I to doubt that ?
Houdini now suggests 5 black moves with a black advantage - surely there will be one that allows black to exchange some pieces ? 12...a6 is recommended, but let's look at 12...Bc6 (diagram)
To me, it seems the attacker has less than anything here. Sure, black has not yet castled and his queen is about to be x-rayed, but all of white's threats can be answered.
Summary, the Zilbermints gambit in the Euwe defense is to be respected, but not to be feared and there are many black lines leading to a black advantage.