User blog comment:Miskos3/Fairy Tail 525: Why Did the Emperor Never Love His Child?, Review/@comment-4829046-20170304191746/@comment-7418318-20170306083209

Wow... I'm surprised anyone actually read this. ^^

I am not surprised at all that Jude wouldn't just not want to make Lucy into a better mage, but might even outright sabotage her attempts in this regard.

For all we know Layla was a great Celestial Spirit Mage, but all that greatness didn't save her. On the contrary, if she had not been such a good mage she might never have attempted to do the ritual without the full set of keys.

So I find it understandable that he would want to keep Lucy mostly away from magic, though considering how much she loves being with her Celestial Spirits I can also understand why he doesn't attempt to take those keys away from her.