Thats the maximum any away team is allowed to take due to segregation, it is a tiny little ground that only holds 5,000 and only has 2 and 3/4 stands currently, so it is understandable.
Appreciate it's not the not the biggest. I was reading that a few years ago Rovers and a few others were given 2,000 though so presumably they just let them have one of their other stands too?