Unfortunately, it applies to EVERY Brasilia flight, not just MRY. Due to the increased average passenger weights introduced in the early 2000's, you'd be lucky to see more than 28 passengers on this plane---unless there were a bunch of kids or very few bags---so 27 would be considered an average "normal" load.

This same reason is why you commonly see weight restrictions on an RJ if there's weather at the destination. It also affects many other airplanes certified before 2000, although most if not all will have enough available payload to play with that they can reduce their maximum cargo payload allowance, and not passenger count.