take a step back and look at the big picture.

N900 is one of only two devices iirc that i can think of that were released with Maemo5, the other was chinese. Scratchbox is a dev environment so there are some bits that don't work fully because the hw is missing.

Neo has similar hw at the core (eg cpu, gpu) and some different (eg eMMC, modem). As there are some similarities, certain components will work as is. the rest will need a new solution, be it a compatibility layer or RE'ing a closed source binary like what has been done for MCE. once this work has been done once is should highlight issue porting to other devices. 2nd device will show if the work done originally is sustainable or if a new solution is needed.

if you drastically change core components, the base os may not even run on the new hardware so where are we then? porting team would have to do a hell of a lot more work just to get to point where they are now. think how many differences there are in hw terms between say an s4 and n900.

then there are infrastructure changes to consider. supporting multiple devices is going to need changes to repos structure. it might need changes to existing n900 packages to pull in hw specific packages depending on device. existing packages might need spliting.

the work being done on the phone they want to work on is going to benefit anyone who wants to port to something else. if you aren't happy with there choice of device, just be thankful for what they're doing as it will help if you try to port to the device you want.