I encountered a Heimer who did exactly what I did in the video during a Co-op vs. AI match. Basically, he tp'ed top at the start of the match, having bought only boots and a pink. He placed the pink over the wall, next to the golems, and then placed a turret behind the wall. Now he was able to just stand at the spot and do nothing while the cannon would permanently be "in combat", causing the AFK detection not to trigger.
Me and my allies tried a lot of stuff to stop him but it didn't work. When we killed the golems, they respawned 1 minute later and Heimer would continue. Killing only the big one didn't work either. He was barely out of range of the red buff and Baron, so none of them could kill him either. We tried pushing hjm away from his turret with Trundle Pillar, but it took too long and he eventually just walked back to the original spot.
As much as I like his creativity, I feel like this should be bannable. What do you guys think?