Changeling Arch-Deceiver ability on objective

[CaptKeiv]

Arch-deceiver: At the start of the battle, you can set up the Changeling in your opponent’s territory as though it were part of their army. Enemy units treat it as part of their own army – they can move within 3" of it but they cannot target it with spells or attacks, and so on. If it attacks, casts or unbinds a spell, or is within 3" of an enemy Hero in your opponent’s hero phase, it is revealed and this ability no longer has an effect.

So can the changeling contest if he isn't revealed?  Because, if I treat him as being in my army, he doesn't contest, but for my opponent, he does. 

Would like your input on that!

[Kramer]

Good question. I assume he cant. To content something is an active thing to do, not passive (although it of course looks that way because you simply move models within a certain range) 

so I assume (keyword) that if the changeling actively contests an objective for the glory of the chaos gods he would reveal himself. 

Especcially as I thought contest is automatically two opposing parties. But I'm not a native English speaker so take that with a grain of salt. 

Curious to hear what other people think. 

[Arkiham]

Most tournaments rule it as he can't unless revealed, which, is fair .