[Call me when humans go extinct]

You are right, you are not using ambient occlusion bug. Because that bug was fixed in 2012 for css. You are just using wallhax.

Your reasoning towards making the ban permanent is pretty low and I'd say random.

Let's say the field of shooting angle behind the smoke is 30 degrees. And the hitbox is around 1 degree. That is 1/30 of possibility to hit 1 shot. In that match you made around 10 kills behind the smoke, average 2 hits per kill, which means you did 20 hits behind the smoke, and made it (1/30)^20 of possibility to do that, and I didn't count in the vertical hitting possibility. If you say that is random, why don't you go buy some lottery tickets.