I feel nostalgic when I see you !

In English, to hunger and to thirst are words with multiple meanings depending on the context used. The literal hunger and thirst obviously refer to the drought and famine his magic can create by doing away with resources. However, in a more positive spin, hunger and thirst are also figurative words, meaning to have a drive for a goal one seeks to accomplish. While Leona could be causing your "hunger and thirst" by drying out your resources, he could very well be the reason you seek to no longer remain stagnate and reach towards a better future, he certainly is for the likes of Ruggie and Jack. Likewise, "I am the one who steals your tomorrow" can be read as dedicating your time to his cause. He is "stealing" you away from perpetual insignificance or trivial endeavors as you face reality with a newfound drive. Even the egregious "kneel before me" can be read as him demanding gratitude for his guidance, rather than a demeaning request after threatening violence. Although it's still a grandiose boast, there is an implication that you'll want to kneel before him once his mission is complete. This would also play into the spirit of persistence that marks Savanaclaw, as hunger (be it a spark of inspiration or a desperate need) creates the drive that makes one persevere in the first place.

His magic is mischaracterized as inherently destructive because of the magnitude of the force he exudes with it, but like in Chapter of Ignihyde, there's nothing destructive about turning falling shards of glass into a trinkle of light sand, in fact it's quite the opposite. Likewise, in chapter of Octavinelle, he is able to sand the contracts, shrapnel and heavy objects thrown the student's way by Azul. These moments reveal its true nature as a disruptive force, rather than destructive, as Leona disrupts the advantage that better mages and stronger agents have over his underclassmen. It could be intentional that both of these are instances where he does away with things that put weaker students at a disadvantage, effectively creating a fairer environment for them to compete and/or win. While he can (and does!) cause harm, its disingenuous to only paint his magic as dangerous, much like how his intentions by those around him are perceived. Leona seeks to disrupt normalcy, not degrade it into chaos like a surface level reading of his magic might cause one to assume. Disruption of abusive or harmful systems or powers isn't inherently a negative action, as he shows that there's actually stability that can be created by doing away with egregious privilege. His magic seeks to change narratives through his own momentum, which of course should inspire those around him to do the same.