I haven't picked up PotA because a) I generally don't buy adventure paths, and b) I haven't heard anything particularly notable about this one. However.
"Get someone else" has been a constant critique of FR since the beginning. As a DM, it's just something you have to deal with. At a lower level of "help", it's worth noting that since The North is primarily city-states, they have a pretty limited area of concern and influence. Standing armies are fabulously expensive to maintain for countries, let alone cities, and it's likely that their remit doesn't extend more than 5-10 miles past the city walls. Ivan Lackland didn't sign up for the City Guard to go tramping through the forest for a week, after all. He signed up to guard the city. A much more likely response from middle-management is to wait until the problem is a lot bigger, and a lot closer, and then wake up Khelben or work out an alliance to deal with it. Until that happens, the PCs can just turn themselves around and take care of things themselves.