I checked with the organisers, and the number is accurate. Most short story competitions that I've been final judge for have had a short list of 15-20 so that means if you entered this competition you would be automatically on the short list.
It has to be said that this competition isn't as prestigious as, say, winning the Bridport Prize and I'm not sure if there's a cash prize, but if there is, it won't be much. But then, if you were entering competitions for the money then I think you'd be better off going in for the lottery. On the other hand, if you were entering competitions for the warm glow of success, or clocking up credits then this would be a great competition to go in for.
Decide what you're looking for - money, prestige, credits - then go for most appropriate competition you can find. If it's credits, then look locally. My first short story success was in a competition run by a local firm of solicitors together with the local paper. I don't know how many entries there were, but I came 2nd and the thrill has kept me going all this time.