he's only considered technical failures because those are the only types of failures that reflect the safety of a particular machine.
Not wanting to get bogged down in semantics but this statement is misleading. If you are considering that a 'technical failure' is defined as some equipment or system not meeting its design intent then these are certainly not 'the only types of failures that reflect the safety of a particular machine'
An aircraft can be perfectly serviceable but have inherent design flaws that can lead to aircrew interacting with the environment in a way that ultimately leads to a crash. These could be issues related to unacceptable workload, mode confusion, inadequate or inappropriately displayed flight parameters amongst many others. Consequently, every incident should be considered part of the safety record until an external and ultimately unavoidable cause to the crash has been determined.
Even enemy action can't be discounted if part of the safety requirements are the proper functioning of DASS and any protective survivability aspects have been considered e.g. inerting fuel tanks for small arms fire etc.
I'm just saying its more complicated than technical failures.