Random or not, the people who used a 3rd party app to idle for extraneous amounts of time...is not really playing the game.  Hence, it is giving an unfair advantage to those who are not actually spending the time to play the game for real.

I understand the concern over this "3rd party app" lingo.  However I think that argument is one of semantics.  This third party app really only simulated idling, not doing achievements.  It was in fact no different than an "actual" server where people launch the game and sit in the "achievement_Idle" map.  So really, to paraphrase a forum post on valve I read, They have only made it inconvenient to idle.

In my opinion these hats are for other people to look at, they are not for the person wearing them.  I have 2 hats, one was unlocked during "play time" and another while sitting in the achievement_Idle map before this third party app was created.  I have un-equipped both.  In effect taking them away from not me but all the people on the server that I would be playing.

If idling would have granted some type of unfair advantage in game I would have agreed with valve.  For the argument that this granted an unfair way to unlock hats, joining an "actual" Idle server would have the same effect (thats how I got a hat).   I think most of not all of this could have been avoided with a warning before labeling people as hacks and cheaters.  With this kind if precedent Valve could just up and decide using, I don't know, a trackball is hacking and ban people with little or no explanation.