Frankly, summoning an evil mob into danger is arguable. I could argue that it isn't against the code to force two evil creatures to kill each other. In general, I'd agree with Matrik that it's a no-go, but I can at least see the argument the other way.
Summoning a neutral sentient creature into a place where you know it is likely going to die? There is absolutely no justification for a paladin to do that.
Your "Paladin Mob" argument doesn't hold water either. A Paladin doesn't get to choose whether another creature should die. Ever. And no Paladin should ever be ok with letting someone else (even another Paladin) die in their place.
Cry of the Phoenix is irrelevant. Anyone can choose to put themselves into danger. The Paladin just can't let them get hurt to save himself. That means if some random Elf thief cries into battle with a Lich, the Paladin can't duck out and let the thief die in his place.
And your last argument is beyond ridiculous. Paladins aren't about getting by on technicalities. I sincerely hope you don't think that's appropriate roleplay on any level.