maybe packetinjection works in maemo and not in NITdroid as when you chroot the maemo kernel is still used which contains also the packet injection drivers. Assuming you have power-kernel 47 or 46wl1.
or am I wrong, I almost dont know anything about chrooting, except its running an OS mounted to some point in another OS

Else I am goint to look at easy debian and make my own image with much bt5 tools included and will post with noob-friendly instructions, but since I am a noob too it can take a little while