You are looking at it from a cheater's perspective and not from a legitimate player's perspective.
The stupidity here is that if the clone will be ignored you are making it too obvious for them to detect it.
Think about it...

You want to approach it as a legit player would.
Think of it if a legit, yet suspicious player doesn't see the clones through walls, but he will face them at some point, right? For him, it's just another player in the lobby.
Now think of if we eliminate that by making them not show up or show as AI, this becomes a straight indication that the "cheater" is well aware of what it is, but in reality, a cheater wouldn't end up in this situation in the first place if he wouldn't be too damn obvious with the cheat.
We have the Legit version and "Show Invisible" feature for a reason.
That's how you prevent from being flagged, by disabling the ability to see through walls and just focusing on what's visible, which is more than enough for this game.

As I already said above, this is mainly on an already suspected/flagged account. So if you got flagged, you already fucked up. It won't help you if you'll ignore it or not.