A person was hired to help out a minyan. He attended but did not daven with them. Most days they managed to have six mispallelim without him. They are only makpid to have six, not ten. On a few occasions it was only five mispallelim. he says that according to Rav Moshe you need ten mispallelim for tefilla btzibbur and since they are not makpid he refuses to daven with them but simply attends without davening and considers their minyan not to be tefilla btzibbur (he davens before or after). Is he entitled to get paid for attending their minyan?
If you are not helping out the minyan, even if it is for the most altruistic reason, you are still not doing what you are getting paid to do. If you were hired to indeed daven with the minyan and you don’t, I don’t see why you would be allowed to take the money. However if you were only hired to babysit the minyan, and just be another person, even if you already davened, then your pay is justified. As a side point the Mishna Berura holds that it is still considered tefilla btzibur if there are six people davening there.