I know with certainty that this case is representative of many such cases during these times of transition. The problem most likely comes down to a handful of parishioners who complained that the Mass is becoming ever more of a serious undertaking and a spiritual challenge and they resent it, longing for the days when the music underscored their own belief that the faith is no big deal, just another superficial life duty we undertake week by week. The pastor was unprepared for this reaction and tossed the musician out, refusing to stand up for what is right.
Cantemus offers this "unsolicited advice to current and future pastors":
You are, or will be, the competent territorial authority regarding the liturgy at the parish level. Learn about the liturgy you are supposed to be caretaking and cultivating, and on whose behalf. Don’t assume you learned all you need to know about liturgy in the seminary, especially about music and its proper execution; chances are good that you didn’t, and besides, isn’t learning a lifelong process for you as well as your faithful? Lastly, take active responsibility for enacting proper liturgy instead of hanging out to dry those people who assist you in good faith under erroneous assumptions. Be proactive, not reactive. You are pastors, not focus-group coordinators. Lead your sheep!
There is another lesson for laypeople who love good liturgical music. You must speak out. You must support musicians who are doing the right thing. You must tell your pastors how important it is to you that the music at Mass be fitting, consistent with our long tradition, and tied to the ritual itself. Your voice is urgently needed in hundreds of parishes in this country.