You'll find some, if not all, details here :
http://forum.shrapnelgames.com/showthread.php?t=45498
The most relevant part imho is the breaking of the forum's own rules. Indeed, it's not a democracy here and everyone should know better than breaking the rules. I mean everyone. Including its moderators as their utmost reponsiblity is to ensure those rules are law, hard as steel.
You know what happens in real life when the police baffle the rights of a prisoner, as guilty as can be? He gets released because of it, regardless of his faults.
If Sombre was indeed that foul-mouthed, he rightly deserved a temporary ban...which he never got. As some have pointed in the above thread they couldn't have made more damage to the forum's integrity by breaking their own rules.
There are weeks that start with a sad, grey and rainy day and this is one of them.