From the CWT rulebook:
1) No visual aids. Visual aids include rulers, straight edges, paper, transparency sheets, or other objects placed on or near your screen. They also include markings on or around your screen, glasses that help you aim in a straight line, programs that display visual overlays on the screen for aiming or measuring, etc. Placing your own unmarked hands on the screen is fine.
That's CWT though, as far as I know it only applies to Intermediate, if not only CWT/ONL.
Right now I can't remember if the TUS scheme is ONL and uses the exact same rules, if it does though that even allows using your thumb or hand on the screen, in fact I've been doing this in most games I've ever played, not just Worms Armageddon. It has other uses than just re-aiming in BnG lol.
Though it's not important for this anyway because even if there was a way to detect people doing this, you don't even NEED to do this to achieve the same thing, you can do it with the game itself.
I mean all of that. Some players don't rely on any of those measures and are at disadvantage because of the reaim rule. If those external visual aids didn't give an advantage, no one would be using them.
Think of it like this, which is something I explained in the thread, which I thought you already knew, or at least MonkeyIsland does which is why it was changed back.
Without auto-reaim, both players can re-aim however they please as long as they reset the angle 45 degrees from it's original position before shooting again.
Now, players who count out their shots usually never need to re-aim anyway as they will hit pretty much 1st time every time at least with full power shots and most others.
Players who play instinctually, they currently have a few comfortable ways of re-aiming back to the position they were at. Both with and without using their hands on the screen.
If you take away that, it changes absolutely nothing for the counters because they count their shot from the reset position that auto-reaim does anyway, so if anything, it saves them a second or so to move the cursor back to the start anyway.
Generally speaking, this makes it much easier for counters to play BnG and gives them an advantage against most players.
The ONLY way to stop people who count BnG shots is hopefully when Deadcode and CyberShadow update the game engine so that there's no such thing as a notch anymore, which will actually render people who rely on notching and counting useless.