While this seems interesting, it really hampers bombers heavily. I would make these monsters invulnerable while inflicted with any status, and have about 200 health (tier 3) maybe? They also have maximum vulnerabilities to all statuses. This would mean a bomber could pacify the special monster, and drop damage bombs immediately after. This also means you can throw vials at these monsters to make them temporarily invincible, and since vials deal about 75 damage or so in tier 3, it wouldn't kill them all that quickly and gives you two vials before they die from a third.

My only question would be if "passive" monsters still attack you, and if they do, perhaps they should be renamed to "cowardly". Once all their allies are dead they refuse to fight you any more, and perhaps they retreat when under a status (since they are invulnerable). This would make them less of collateral damage and more of a challenge to deal with, while also giving vials a pretty powerful niche.

They wouldn't hamper bombers that much if they don't follow the player around like normal enemies do.

Seems like a neat idea. My only gripe is that I'm a nostalgic sod and would rather see gold enemies as invulnerable and aggressive than passive loot-hoarders. :P So the only thing I would change is making them silver (or platinum) coloured instead. Or perhaps drop the colour entirely and give them something akin to the nature/flower aura (whatever its name is, I have been gone for too long) to indicate their friendliness.