Interesting theory, I am actually thinking right now that it might even be one step easier considering what just happened to me:
I have two Xbox360's, both on 1.6, always play games with perfect abgx stealth. I always check the stealth and crc after burning, always checked out. I have never put a disc into any of the Xboxes that didn't have perfect stealth.
Now one of the boxes got banned, the other didn't (I use two different Live Accounts on them). The only difference: The one that got banned had a game (backup) installed on the HDD. I have never used the HDD game install before but I had the well known Beatles Rock Band black screen problem which many people said could be solved by installing the game on the HDD, so I went ahead and did it. It solved the problem, but it possibly also got the console banned
It might be stupid thinking, but could somebody please reply who got banned and never had a game installed on his HDD? It might just be that the HDD install messes it up? Just a thought

I used to be a PS fanboy untill I played Gears of War 1 on my brother's xbox, as I became addicted to it I bought myself an xbox 360 and the game.
Unfortunately the gears of war DVD would work for 1-3 months only then I'll get the can't read disk error.
I ended up buying Gears of War 3 times, when Gears of War 2 came out I was very busy playing Gears1 on the computer (loved using keyboard and mouse on my favorite game).
So I didn't rush in to buy Gears2 especially because alot of my friends said that it was nothing like gears1 etc etc.
When the pc community for gears1 was almost dead, I went ahead and bought gears2 for xbox 360.
At that time they did not have the option for the HD install (could be wrong) at least I wasn't aware of it.
So one day I was browsing through the ads on my local craigslist and saw and ad for flashing xbox's to ixtreme firmware for only $25 and I called the guy and had him flash my xbox, I believe was ixtreme 1.5 or 1.4 can't remeber... anyways I ended up never making a backup of the original gears of war 2 game as I traded to gamestop a few days after I beat the campaign because I really HATED the multiplayer compared to the first gears.
So I read somewhere about the abgx360 and the new 3/4th wave games... and decided to update de firmware to 1.6 like 2 weeks ago and even though I haven't played a single backup in the 3-4 years old xbox I was banned from live yesterday.
That's why I think the reason for the ban has to be something else.