vilas
You argue appropriately that automation alone was not the dominant issue; however stating poor human performance - 'a day off', 'should have checked', is hindsight and does not consider why … pilots have 'poor days', or why they do not check every cue on every approach.
Captn Bloggs
Developing your question re inappropriate use of autoflight modes … they are used because they are there.
Systems are designed to meet specific needs; open descent is an asset in many situations, but not so in others - joining the GS from above. Thus a piloting task is to understand when a specific mode should / should not be used. Many modern aircraft have inhibitors to exclude inappropriate use, but for each preventative design there is a risk of an unforeseen outcome.
Also, if avoiding capture of GS from above was a consideration (false GS) then is this risk any greater than encountering the situation in this incident.
A balancing argument is that as disturbing this situation appears to have been, the mitigating features resulted in a safe outcome. How often are these situations encountered, how often are the industry safety systems aware of them.