Is it possible that Apple built the userland binaries with earmv6hf or similar?
Perhaps you might want to try non-hardware floating point? It's been a while since I played with getting a chroot running on an Airport, but I seem to remember skipping hardware floating point. I don't remember if there was a reason for me doing thay.
Chicken/egg problem. It is weird that the NetBSD 6.0 evbarm set (comp.tgz) contains a GCC toolset that is not able to compile for this router/nas which runs NetBSD 6.0. Perhaps Apple had access to a toolchain provided by Broadcom for this BCM53019 SOC.
At one time I set up a Raspberry Pi with NetBSD 6 to compile things for use on an Airport. Perhaps I still have those files somewhere. I'll have to look.
BTW; why does the NetBSD community not keep the packages archives for older versions; the binaries for the OS are kept but not the packages unfortunately...I think its a combination of disk space and providing older packages with known security issuesGranted. But you would expect that somewhere, someone has such an archive. But no.
I don't think anything got deleted off of the NetBSD FTP server. Have you tried these pkgsrc packages?
/pub/pkgsrc/packages/NetBSD/arm/6.0_2014Q1/All/ John