Was the honeydew perhaps left in the background of the scene by a crew guy?
i think him choosing to try it was a metaphor for change
i kind of take it as a sign of bojacks reluctance to improve. hes content sitting there and complaining about the honeydew instead of getting a better fruit cup, buying fruit and making a good fruit cup himself, buying something else that doesn’t have fruit in it, or even just not eating the honeydew. by comparison mr peanutbutter is also stuck in the mental age he got famous in like bojack but mr peanutbutter is able to enact change on the world where bojack wont change the world or himself when it would benefit him. mr peanutbutter would probably complain about the lack on honeydew and think of creating the change (fruit bowls without honeydew in them) before losing track of that project because he hasnt grown out of being a distractable young man
compare them both to someone like todd, who by the end of the show not only has realized his capacity to change (like mr peanutbutter has started to after dating pickles) but has also acted on his capacity to change himself and the world around him. todd would have no problem with just getting or making a better fruit cup, for himself or the world