Despite always ranting about honeydew Bojack never ate some as far as we know - or at least not in a long time. When he finally tried it he noticed ist wasn’t as bad as he thought or remembered. In any case it shows his changes as he is willing to try something he thought he hates and accept the result. Old Bojack may have gone ‘well it isn’t thaaat bad but not as good as other stuff they probably just buy it because it is the cheapest option, even at a buffet in Hollywoo you can be sure to get proper food, why am I a star if they offer me the second best stuff blablabla’, grasping for any reason to turn his pleasant discovery into a bad expierence. But since he chamged he simply accepts it as the nice surprise it is, finally letting go of the negativity his upbringing drilled into him.