So I guess we should use matzos, right?
If you are a priest, then you should use something that you are morally certain is not only valid, but conforms to what the tradition that you are celebrating in employs. The East and the West do things differently to highlight different theological truths (the West emphasizes the element of continuity in the transformation of the old ways by maintaining the outer resemblance of the old ways in a particular manner, the East emphasizes the discontinuity in the transformation by introducing very deliberately what was forbidden but symbolizes life). Buying your stuff from a Jewish baker or someone who imitates current Jewish practice is not something that has been emphasized because it doesn’t emphasize, and probably misleads, with regards to theological truth.
If you aren’t a priest but the priest is messing with the matter, it is a very good indication that you ought to drop the Bishop a note and switch parishes.