Newer NRF firmware versions do not use safelink for the bootloader commands, see https://github.com/bitcraze/crazyflie2-nrf-firmware/issues/19 and https://github.com/bitcraze/crazyflie2-nrf-firmware/issues/33. Related issue: https://github.com/USC-ACTLab/crazyswarm/issues/174.
Newer NRF firmware versions do not use safelink for the bootloader commands, see bitcraze/crazyflie2-nrf-firmware#19 and bitcraze/crazyflie2-nrf-firmware#33.
Related issue: USC-ACTLab/crazyswarm#174.