The first transmission from ATC to the pilot was maintain 5000’ which the pilot accepted but then either chose not, or was unable, to do. They descended below that assigned level and were then issued further descent.
ATC then specifically asked the pilot whether they were capable of maintaining altitude and advised that if they were unable, that YSRI aerodrome was 2nm away. They got another non-committal response, the aircraft overflew YSRI, and the rest is tragic history.
Your assertion that a controller would deliberately put an IFER (in-flight emergency response) aircraft in increased danger because it suited their airspace layout or traffic management is disgusting.