According to the Nechreeal OSRS Wiki page (http://oldschoolrunescape.wikia.com/wiki/Nechryael),
"death spawns will not be summoned if the Nechrygaj is unable to attack the player back (such as when being safespotted)."
(https://i.imgur.com/aHHde2j.png)
The Death Spawns still spawn even though I'm safe spotting the Nechywerall.