I think you're missing something. In Parson's first agreement with Charlie, Parson says Charlie is "bowing out", but in the same conversation(with Wanda) Parson warns that Charlie might attack himself on Charlie's turn. Here, Parson talks Charlie out of not attacking the garrison(as expected). He only gives Parson one thing of value in that conversation, and that is ending turn. That, in itself, prevents Charlie from going on the offensive. Also, Parson specifically says here that he doesn't "trust Charlie not to shoot them down", with them being WAF. The whole conversation between Parson and Maggie is about if its safe to send the WAF through Charlie's forces to attack Ansom. When Parson contacts Charlie(same comic), Charlie doesn't say anything like 'we agreed I wouldn't', but rather more like 'I have no reason to want to'. No one ever indicates that Charlie is under a cease-fire with Parson.