I agree and share your thoughts Crab, but I think that the ”radar set up” was also one key factor in order to avoid this sad accident...
I’d like visualize my thoughts with some hypotetic radar pictures (taken from AW139). Btw. The red radar echo is a faulty echo from radar radome,
which seems to be at approximately 0,4 NM distance with WX mode.
If the radar was on 10 NM scale/WX mode it will be almost impossible to detect the targets, when they appear closer than 0,5 NM.