There is a confusion with words here that should be clarified.
If a priest lacks permission from his religious superior (if he’s a religious) or from the local bishop (if he’s secular), if the priest is suspended, for whatever reason, the mass is illicit.
If the priest does something illegal during the mass, whatever it may be, the mass is still licit. The action itself is illicit, not the entire mass.
It is incorrect to refer to a mass as illicit, because the priest does something against the rules. The specific action is illicit, not the entire mass.
That’s a big difference. You can have a priest who follows all the rules, bu is suspended, as is the case with the priests of the SSPX, then the entire mass is illicit or in our language, illegal.
Validity is not the same a licit. Don’t confuse the terms.
Catholics should not attend an illicit mass if there is a licit mass available to them. In the case of the EF, the Sacred Congregation on Divine Worship and the Ecclesia Dei Commission has amplified the permission to allow Catholics to atten the EF at an SSPX chapel to fulfill their Sunday obligation, but there is a cautionary note in place. Those Catholics who choose to attend, should not encourage or support the separation of the SSPX from the Vatican. We’re still bound to the Holy See.
For this reason, about 13 groups have separated from the SSPX in search of union with the Holy See and a lifting of the suspensions of their deacons and priests.
Fraternally,
Br. JR, OSF