Just speculating here: One of the big problems facing secular priests right now is that they are cut off if there are charges brought up against them. I have been told recently that in New Orleans it is so bad that just an accusation will get a secular preist ousted and he must fend for himself with housing, health care, and funds for a lawyer. This becomes almost impossible for them unless they have family or their (former)parishioners help them. There is a growing belief that some priests are being falsely accused and then tossed aside by their diocese. So, I doubt the Chancery would take too much notice right now of a few priests marching outside their offices to be allowed to say the Tridentine Mass.
Arggghhhhh!!! without housing, health care, and funds for a lawyer.