Yeah I think it was more the fact we cut up a lot of wood that can have sand, dirt and fine rocks etc in it that he was refering to in regards to the square filing not being worth the effort due to those issues, he reckons it cuts quicker but dulls quicker doe to above.
I've never tried a square filed chain so have nothing to go by in regards as to whether its true or not but he cuts firewood regularly and races saws regularly and has tried the square filed chain in a firewood cutting scenario and didn't recommend it (I think it went dull fairly quickly in the dirty wood) hence his recommendation of not bothering with square filiing for firewood cutting duties.