He's cleared of conducting Secret diplomacy, as stated in rule 2:
"Any form of diplomatic discussion between opponents must be posted in the game chat in English or in a language that all opponents understand. Diplomacy includes, but is not limited to: proposing truces, negotiating alliances, and coordinating assaults."
Asking for a truce or a coordinated assault IN game chat is not against the rules.
We shall go on to the end,we shall fight in France,we shall fight on the seas and we shall fight in the air,we shall defend our land whatever the cost may be we shall fight on the beaches we shall fight on the landing grounds WE SHALL NEVER SURRENDER