Velk,
I agree that the optional coup de grace rules in AD&D should be tempered with common sense. Of course, the mage might just have a dagger with him...that's a common purchase for L1 magi. And the AD&D golems required magical weapons to hit, which of course I addressed in a prior post. You are correct...the golem would not be slain without magical weapons even if it were paralyzed. Of course, let's remember that NT Jedi's example was that of a red dragon.
The explanations offered by Pillin and Aikamun make sense to me. Because let's face it...thousands of folks in the province. Even if they run away in fear a few times, they can always come back the next day and help some more. After all, it is a whole month.
Norfleet,
Most units have better weapons than forks or herrings.

And I would count all the units able to reach the creature in question after it becomes helpless with no defenders. Not just those still around at turn 50.
NT Jedi,
Even folks who take your side in this discussion of what should happen to paralyzed supercombatants...some of these folks side with me on the red dragon issue. They could gouge out its eyes or slit its throat. Keep in mind that level of experience (unless magical items are present) doesn't have anything to do with the damage done per attack in AD&D, though it may increase the number of attacks you receive per combat round.
The devs have decided to kill these paralyzed creatures, and I agree with them. Paralyze should be less effective now, which I'm sure will make you a bit happier with regard to the survivability of your supercombatants.
Norfleet,
I don't think the present rules truly account for "helplessness." Protection still remains, in my opinion, too effective a counter to blows once one is paralyzed. And I think you know how effective protection is in this game. If your protection is significantly greater than your opponents' damage plus strength, you will rarely take damage. While that makes sense before you are paralyzed, I think it makes less sense, except possibly in the case of immobile hunks of rock, once you are helpless with no defenders. Defense skill of zero isn't really sufficient to model helplessness. Because the helpless creature's armor can be removed...it can't prevent that. The magical accourtrements can likewise be removed...it can't prevent that. And small chinks in spell protection could also be removed or dispelled by skilled magi. (One thing we don't have in Dom 2 that I think would be neat is a form of "dispel magic.")
You have a point with regard to the protection spells which damage attackers. And my answer that they are countered may not prove satisfactory to you because there is no such counter in the game mechanics. Of course...what is possible once one is helpless with regard to enchantments should be different than what is possible if one is hale and moving about the battlefield.
Graeme Dice,
Paralyzation under this system does not become as good as soul slay. The autokill does not go into effect until the unit is helpless and without any defenders whatsoever. Soul slay can slay units even if defenders are present on the battlefield. For paralysis to be as effective, the side using the paralysis must win the battle. Soul slay will kill units even without winning the battle. I view that difference as significant.
The unit itself counts. You specified a spellcasting sphinx. My scenario would not say that a spellcasting sphinx is helpless unless it were paralyzed or otherwise rendered helpless. If they don't move from their fortresses, as in patch 2.08, then choosing a fortress with defenders would render the sphinx always non-helpless. Same goes for the head. However, if a soulless has a month to rip apart a helpless sphinx...well, that soulless must have undead leadership or it wouldn't be on the battlefield at all. So the soulless and its undead leader slowly manage to chip away at the head of the sphinx, not sleeping because they are undead and require no sleep, over a period of an entire Calendar month, thereby expelling the vile spirit that inhabited the sphinx into the void.