Confirmed on the DB - same root cause as the Echeyakee report: a missing spell set.
The mob side is scripted correctly - the Grol'dom Net (item 46722) is meant to cast spell 65580 on a Razormane Pillager (NPC 34503), and the Pillager's SmartAI is fully wired for it: SPELLHIT on 65580, switch to friendly faction 35, an 8 second window, gossip 10519 to pounce, capture spell 65595, then despawn and credit.
The problem is the spells don't exist. 65580 (net), 65581 (ensnare) and 65595 (pounce) all return zero rows in spell_dbc and spelleffect_dbc. So the net casts nothing, the SPELLHIT event never fires, and the Pillager just stays hostile and resets when you move away - exactly what you're seeing.
Fix direction: restore the Grol'dom capture spell set (65580 / 65581 / 65595) into spell_dbc and spelleffect_dbc. The creature script, gossip and the whole SmartAI chain are already in place, so once the spells exist the chain should fire.