Eh, I would not get overly conspiratorial here. Stanley is to much a wild card to make solid plans around.
I think Charlie had little interest in the conflict until he got Parson's mathamancy offer, and then became primarily interested in the bracer. The bracer is a really powerful tool for a mercenary. Consider the current financial crisis. It has its roots in assets being assest for risk, i.e. sub prime mortgages were sold as AAA bonds or something like that. While Charlie can undoubtedly figure a lot of this out on his own, having the bracer to do the more complex and more uncertain bet hedges would be invaluable. For example, just asking what is the highest price that has a 90% chance of being accepted would be a great way to insure business without leaving money on the table.
So, his offer to turn Parson had nothing to do with his status as the perfect Warlord, but everything to do with his Mathamancy link. Charlie might not even have planned on keeping Parson around if the Bracer worked without him. Yet, he backed off for a chacne to grab the Bracers, the Pliers, and/or get another big paycheck from the RCC2.
Now, back to Trammennis. The potatoe comment is a fat joke, but think about what Charlie said. He called Parson "the most dangerous being in Erfworld." More dangerous than than Wanda and her unholy army? More dangerous than Madman with the Hammer that set his side upon a path of total conquest and destruction? More dangerous than the secretive Overlord that just ended a side's turn at an most opportune time? Right now, all Charlie is offering that Parson is a threat is his word, and Tramm has every reason to be suspicious.
Of course, reading the dossier might change his mind. Afterall, there has to be some explanation for Charlie's involvement against GK. One final note, Charlie's bounty money would presumably come after the battle, meaning it wouldn't save Jetstone should Slately die during the battle. Charlie was trying to further push his offer to get a captured Archon returned to him. With Jetstone's general animosity towards Charlie right now, they may very well tell him to keep his money and this is the closest chance Charlie has ever had to capture a decrypted Archon.
@Night Seraph: Another option is a battle where GK almost succeeds, but ultimately fails at terrible cost. I also think Jack is a good enough Foolamancer that he could hide in the city for the remainder of the turn and otherwise escape with any units still vital to plot. I do not think Wanda is, but Ossomer could be interesting to keep around.
"Act, and God will Act." - Joan of Arc
"Those who plot the destruction of others often perish in the attempt." - Thomas Moore