Could be, but why would they have their children in RE (and preparing for First Communion) at a parish where they won't attend Mass?
At the parishes here, the RE director runs the program, with little to no input from the pastor (the "liturgical committees" probably work the same way, but that's a different problem). At another local parish, the RE director is very conservative, while the pastor is, well... less so, to put it kindly. I would never attend mass there, but I would probably let my kids go to RE. The cafeteria is far from closed here in the trenches.