How the data is transferred over the BLE link has nothing whatsoever to do with whether the nRF51 (which is an ARM Cortex-M0) is big or little endian.
As already noted in the previous thread, the BLE link is simply a stream of bytes - it gives no significance to what those bytes represent, nor how they are to be interpreted (other than as defined in any standard Profile you may be using).
It's just the same as sending data over a UART link: you can send the low byte first, or the high byte first; it makes absolutely no difference whatsoever to the UART - they are all just bytes.
If you were to display that on a terminal, it would just show the first byte first - it would have no idea whether it formed part of a larger value nor, therefore, what part it represented.
