He made 3 mistakes that I can see. He didn't manage the basic glide well, he allowed ATC to vector him towards the airfield (instead of doing it himself), and he failed fatality to manage the approach phase towards the runway.
Going back to the beginning, while you may be quite right with the above remarks, the report makes it clear that this was a stall and spin accident.
Certainly, since it happened during a forced landing attempt, the distractions and stress of dealing with an engine failure will not have helped concentration on handling the aircraft but in the end his mistake was to stall and spin inadvertently.
As for your concern about taking ATC vectors I am not sure I understand that. There are fixed wing procedures where ATC can be of enormous help in setting up a good final approach - defined as being lined up with the centreline and 2000 feet above the glidepath at three miles so that you are ideally set up to make your own visually based decisions on when to lower gear, flap, or sideslip in order to plop onto the numbers.
I do not know whether this ATC unit offered such a service (or even had controllers trained in them) - but I don't think we should rule out their potential for help in the right circumstances.