Did you read Canon 120?  I doubt it.  You don't know what you are talking about.

Privilegium Fori, of very ancient origin in the Church, has a certain remote sanction in Holy Scripture (1 Cor. 6:1).

In all contentious or criminal cases clerics are to be summoned before an ecclesiastical judge, unless lawful provision to the contrary has been made for particular places (c. 120, S 1).

[Fr Sanborn was a cleric.  So +Lefebvre was obligated to bring him before an ecclesiastical court.  Which court would that be Croix de Fer?]

Cardinals, Legates of the Holy See, Bishops even though merely titular, Abbots and Prelates nullius, the highest superiors of religious societies of pontifical law, and the major officials of the Roman Curia in matters pertaining to their office, may not be summoned before a lay judge without permission of the Holy See; other clerics who have the privilege of the forum may not be so summoned without the permission of the Ordinary of the place where the case is in progress; the Ordinary however, shall not refuse such permission without a just and grave reason, especially if the plaintiff is a layman, and more especially after he shall have tried in vain to effect a compromise between the parties (c. 120, S 2).

[+Lefebvre was not a sede at the time so presumably he should have sought permission of the Ordinary to file the lawsuit against Fr Sanborn et al.  But he did not for obvious reasons.  But from the forgoing, it is clear that in normal circuмstances the permission would have been given and how much more would the Holy See (if it existed) be obligated to permit Fr Sanborn to defend himself!  Idiot!]

Clemens Mangina says:
you should just shut your mouth about stuff you know nothing about.