Our job as parents is to populate heaven. Whatever children God gives you the responsibility to get there, is up to Him. The priests should not be dictating to the congregation how many children a family should have. That is GOD'S business and not theirs. If God deigned to send 3 children to one family, and 10 to another, that's HIS business. Surely if someone would be hindering the primary end of marriage, THEN something should be said, but a priest certainly SHOULD NOT try to say how many children is "too many."
Good grief, the flood of souls going to Hell now, is at a disturbing high, and the priests are going to say that Traditional Catholic families should only have LESS than 6 children? Who do they think they are!? GOD IS SENDING THE STRONGEST SOULS HERE NOW, for the battle is going to be even more difficult. This kind of counsel from a priest is nothing short of demonic.