Depends on which charges. VB claims xenforo was created while KAM worked for them, and on that grounds xenforo is their property. This claim can be easily disproved by the SVN repo and other such tidbits.
Claims of copyright infringement would usually carry huge fines, so worst case, Xenforo Limited would have to shut down as they would not have enough liquid to pay vBulletin. ABSOLUTE worst case, KAM could potentially carry jail time on the wire fraud and hacking charges.
Incorrect. Laws are in place to stop that situation, the only way that would work is if Xenforo SELLS the code to vBulletin to pay for costs. However, as XFL is a limited company, there is a nice loophole.
Assuming they lose, KAM auction of the software rights in the UK via a liquidation company and shuts down. I buy those rights to the code, set up a new company and hire KAM.