Woah, there. Hold up. Full stop.

I think you read the ending to the PLD 60 quest wrong. We aren't crushing Constaint's dream at all. Solkzagyl, bastard that he is, was manipulating everything behind the scenes to give Constaint a suitable origin story to shape him into a "true Paladin," but that's all it was: manipulation. Even Constaint realizes that something is up, and the end result is that he isn't truly able to gain a Paladin's strength. Beating him isn't taking the light of his crystal forever and stripping him of his abilities (though if that were the case, it would explain why Jenlyns is so useless), but simply asserting that, given the circumstances, you are the stronger.

The way I see it, the entire thing was more about defeating Solkzagyl and his flawed teaching logic. We won because we were the closest to the ideal Paladin, neither manipulating others nor being handed our powers on a platter. Solkzagyl is a bastard, plain and simple, so there is no way in all the seven hells I would let him beat me, and poor Constaint, who has all the qualities to become a great Paladin, wasn't given the opportunity to achieve that through his own strength, instead being led along a lined path towards the "destiny" Solkzagyl had decided for him. Simply having the gear, the crystal, and some semblance of an adventure, rounded out with a tragic origin story doesn't make a Paladin.

When Constaint leaves at the end, though, his dream isn't destroyed and he isn't giving up on becoming a Paladin. He even keeps the soul crystal and gear, neither of which would be possible if he wasn't worthy to begin with (since the crystal has to choose). He's just going to follow your example and become one on his own, without the shortcuts, so he can challenge you again.