There is a question here, at least for me, of whether or not the priest knows that these people are requesting a dispensation because of their distate for the standard Mass of the Roman rite
– called pejoratively by some the “Novus Ordo Mass.” It is very possible that they may be saying to him, “Father, I’m going to be out of town next week and don’t think I’ll be able to find a Mass to attend. May I be dispensed from the Sunday obligation?”
If this is how the requests are being presented, then it is Catholic teaching that one can be dispensed from the Sunday obligation if traveling in an area where he cannot attend, or does not foresee being able to attend, Mass. It would be the parishioners’ responsibility to make clear that their problem is not that they cannot foresee being able to attend Mass, but that they cannot foresee being able to attend a Mass tailored to their preferences. If they have not made clear the entire situation, a priest can hardly be faulted for giving them an answer that is correct according to the situation as he understands it to be but incorrect according to the situation as it really is.
If you have firsthand knowledge that people are requesting dispensations under false pretenses, you can certainly enlighten the priest to the underlying dynamics at work under these requests. If, however, you have firsthand knowledge that the priest is actually dispensing people from the Sunday obligation so that they will not have to attend a standard Mass of the Roman rite, I recommend discussing the situation with him to ascertain his thinking on the matter. If you cannot dissuade him from the practice, I suggest reporting the situation to his superiors in the Priestly Fraternity of St. Peter (FSSP), an orthodox group that is in union with the Catholic Church. If that still does not resolve the situation, take it to your diocese since this is a diocesan-approved indult Tridentine Mass that you attend.