Without wishing to comment in specifics of the accident :
I'm hazarding a guess that he didn't have low-level flying training and qualifications?
FWIW the dangers/differences between upwind and downwind turns at low level were regarded as so significant that they used to be taught or at least demonstrated by (UK) Central Flying School instructors as part of the first low level flying lesson on a light piston aircraft , I'd guess/hope it's still taught elsewhere. As someone has already pointed out the major threat was regarded as trying to tighten a downwind turn or "wrap a turn up" to overfly a ground datum.