Well, I don't know about excommunication, but here's what Canon Law says:
Can. 278 §3. Clerics are to refrain from establishing or participating in associations whose purpose or activity cannot be reconciled with the obligations proper to the clerical state or can prevent the diligent fulfillment of the function entrusted to them by competent ecclesiastical authority.
Can. 273 Clerics are bound by a special obligation to show reverence and obedience to the Supreme Pontiff and their own ordinary.
Can. 1389 §1. A person who abuses an ecclesiastical power or function is to be punished according to the gravity of the act or omission, not excluding privation of office, unless a law or precept has already established the penalty for this abuse.
§2. A person who through culpable negligence illegitimately places or omits an act of ecclesiastical power, ministry, or function with harm to another is to be punished with a just penalty.Can. 1399 In addition to the cases established here or in other laws, the external violation of a divine or canonical law can be punished by a just penalty only when the special gravity of the violation demands punishment and there is an urgent need to prevent or repair scandals.
He could and should be given direction under obedience to his Superior to resign from this board and to repudiate his actions.
If he does this, Christian charity binds us to forgive him. If not, then his Superior should ramp it up until Jenkins' attention is gotten.
CAUTION: I am not a canonist. Therefore, I may have missed something. Take the above as the words of a barracks lawyer.
Your knowledge of Canon Law is impressive — JCL or STL after your name?