The lack of knowledge and associated hubris from a number of posters on this thread is a classic example of the primary reason that the bulk of airline managers hold their pilot group in contempt.
Not all pilots of course, but at least those in their ranks that believe they know it all, because "I'm a captain" and they then vocalise their lack of understanding. As a former commander (both domestic and international) if personally find it embarrassing.
There are a great number of 'barriers to entry' in the aviation industry and access to terminals and their facilities is one of the more prominent. Talk to any of those that have tried and failed to enter the industry and they will not be at all surprised that access to check-in resources is delaying the start of a route. This is not uncommon and a perfectly valid reason for a delay.
The idea that a GA asset can be utilised and passengers bussed to that resource may sound simple and an obvious fix, however the successful entry into a market requires a point of difference that makes the experience less complex and more pleasurable. I would humbly suggest that the use of GA assets would provide the opposite experience, which means the inconvenience of a stop-over, yet with the gathering of frequent flyer points with one of the majors, suddenly looks just fine.