[SynSid]

It's a perfectly valid tactic - whether or not it was an appropriate one to use here is hard to tell without more information (in particular, how the 2nd place stack is playing).

I've folded AA to a push from a short-stack before on the bubble in a tournament. Taking his small stack was worth far less to me than another round or two of taking blinds off the rest on the table. I was the big stack by a mile on the table (not the biggest stack in tournament though) and the rest of table were just trying to fold their way into the money - in that situation bursting the bubble is the last thing I wanted to do.

If the big stack in this game was convinced the 2nd stack was just trying to fold his way to 2nd then keeping the short stack alive could well have made sense. Looking at the stack sizes I'm not at all convinced it was a good choice by him even then - but there's no reason to assume it was cheating.