Duncan Shearer was getting caps ahead of Coyne so I don't think that's true. Roxburgh made a lot of strange selection choices and for some reason seemed to favour Aberdeen players like Shearer, Irvine and McKimmie who were pish.
The grandparent rule levels the playing field for countries with high levels of emigration. If the SFA don't find a goalscorer from outwith Scotland it'll be another wasted decade because you can't do anything with the likes of Nesbit, Shankland, Watt, May, Kane or Clark up front.