Intentional lag switching in arena

I recently experienced this from a warlock a few times in arena (I won't mention name, neither I am here to report anyone) but is this allowed? Yes, it's hard to prove that someone is really doing it intentionally but it ruins the game and when you see someone laging in critical situations and doing perfectly fine when he outplays you, then you know what is really happening... The guy wasn't just laging, he was doing this when he was about to die or we were bursting.

For people that don't know what this is - it's making yourself laging intentionally (there are simple macros for this) in order to prevent other players to intercept you, target you, see your real position etc.

Chance is high that he lagged intentional since its so terrible easy to set that up.
When I do arena I always run bandicam in the background and start recording as soon as something looks fishy. Should be easy to tell the difference between somebody with a bad internet connection and somebody lagging only in crucial moments.