Taking nothing away from White because I haven't seen him play, I question why Ben Hall is not the backup considering he is older and has first team experience albeit with Motherwell.
Haven't seen him play but he only had 18 first team league matches there - including 0-7 beating by Celtic, 0-6 by Hearts, 1-4 by Aberdeen. I for one would be a bit concerned to see him make his debut in one of the hardest away fixtures of the season.