If this does turn out to be a ballsup, the fact of the matter is that the system let these two pilots get to where they got.
Possibly but you could say that about any human endeavour.
Short of a deliberate yahoo "I'm gunna try a low level run around town on one donk with the gear down because all that ops manual stuff is rubbish"
Unfortunately, that appears to be what they did. They had an Ops Manual which one would have hoped at least the captain had a passing familiarity with, especially concerning a engine failure on takeoff and the associated drills, on the basis of self-preservation let alone professional standards.
They got the aeroplane back on the ground in one piece despite making life very difficult for themselves.
But it should have been a non-event. If this had happened in the USA, they'd be looking at 'reckless endangerment'.
Let's learn from it instead of asking "WTF were you thinking?"
OK, what can we learn? Don't put the gear down following an EFATO and do a low-level cruise around a big city with the other engine on a random power setting...?
I'm in the camp that would really like to know "WTF were you thinking?" so I can avoid the trap that got them in this situation, assuming that it wasn't just blind panic, lack of knowledge, low standards, poor CRM, etc.