Mon'tregul's Grasp explosion only applies to attack hits

Mon'tregul's Grasp suggests that enemies killed by Zombie's hits will explode, but it only seems to apply to their attack hits. Hits from Minion Instability do not cause explosions, and hits from the explosion itself do not chain further explosions.

Both of these hits are clearly attributed to the Zombie because equiping Cold Iron Point on the player does not prevent their damage, and the player does not benefit from on-hit or on-kill effects. Profane Bloom, which similarly suggests that cursed enemies killed by minions will explode, does cause explosions from Minion Instability hits.

Demonstration video with context: https://www.youtube.com/watch?v=LLBrRrKe9ww
Path of Building for demo character: https://pobb.in/1mvXktAHx_u5

The plain solution would be to reword the mod to say that enemies killed by Zombie's attack hits explode, but it feels like a missed opportunity to not allow Minion Instability hits to trigger them, given the item's natural synergy with it.