because in doing this you are assuming he's playing decent ICM poker. in this case because you're so short-stacked, his all-in range will be very wide. Q9o is a decent hand, it will be ahead a lot of the time. Also you have already committed 1/5 of your stack in posting the big blind and you need to make a move soon.
in a real tournament, especially at the 1$ and 5$ levels, call ranges in ICM are 99% useless. the opponents will not be playing ICM and you have to analyse each situation case-by-case.
btw that's not to say shove ranges should change. if ICM says that is a push in that situation, regardless of what table you are it's going to be worthwhile to do it