I see, you did argue already, like me, that ARO should be lost, not turned into Idle. but HellLois ruled in favour of IJW argument that ZoC ARO you shouldn't have had turns into valid Idle ARO and for example can be used to tank a Mine; or in this case, reveal a HD.
Stepping aside from the highly technical "what happens when you declare an illegal aro from hidden deployment" question, I've seen this sort of list question comes up sometimes and it kind of rubs me the wrong way. Some people are trying to be way too cute about making lists that are essentially off the board for the first turn of the game. There are reasons a lot of other games have limits on how many models you can deploy via alternate means.
Cute or not its valid. Theres inherent risks in that it relies on your opponent to play along and if anything goes wrong you are absolutely sunk. But its legal and shouldnt be looked down on merely for trying it
What you see as "cute" others enjoy as clever. Personally I just want the rules to be understood and have a easy to fallow logic to them.
To be honest, even if full hidden deployment lists became a thing now, there is no reason to be worried. Those list would be just overpriced, and they would be wasting TO for a really unimportant trick.
Ok, fair. But every time I've seen someone try to do this they play it incorrectly and try to have the model declaring Alert and/or the other activated models that declare Change Facing as a result of that alert come on as TO Camo makers instead of going to a fully revealed state.
Then you need to tell them they are doing it wrong. because they are. And thats probably the biggest problem with this as a "tactic" that its fragile as frak and if you mess it up, you end up with a bunch of dead expensive dudes
If you run into one like that, just use up a few of your orders positioning things and pass with some unspent. If their game depends on you being predictable so they can sneak out at the last second, don't be predictable.