Killua hates assorted chocolate because all the different flavors usually suck but eats all the assorted boxes of chocolate Gone gives him. Not because he loves Gon but because "any chocolate given to me cannot, will not and SHALL not be wasted"
I can totally see this happening haha XD Killua would probably like ‘plain’ chocolate the best bc that’s the flavor he’s interested in, not the weird strawberry or orange filling in some of the assorted chocolate stuff. Like, if he wanted strawberries or oranges he would get some but when he wants chocolate he wants chocolate chocolate.
But like you said, Killua would never waste chocolate. No way. He would rather get sick from eating too much chocolate then to throw it away- not that he could get sick from doing that but you get the point.
…imagine Gon getting the assorted chocolate boxes on purpose just to see the weird faces Killua pulls whenever eating a bizarre flavor of chocolate like coconut or peach hahahaha XD
“But, Killua I thought you like allllll kinds of chocolate.”
“I do, okay! This is just…weird, though. Are you sure there wasn’t any plain chocolate in the hotel lobby? Like, not even a normal chocolate bar or something?”
*cue innocent blinking* “No, I don’t think so! But I figured you would still like chocolate anyway, so I got it. You don’t like it?”
“Well, yeah, of course I like it. Chocolate is chocolate, but- oh, c’mon!”
“What is it?”
“This one is ‘goat cheese flavored’! What the hell?! Who came up with this crap?!”
And then Gon falls over from laughing so hard XD