Killers presence on the roof is quite significant in terms of establishing his and Zoro's roles.
I know that the desired narrative is to paint Zoro as Luffy's peer when it comes to a small vocal chunk of Zoro's fanbase, but we're not really getting that with this lineup making it to the roof.
Instead Zoro and Killer are obviously up there as main subordinates of Luffy and Kidd, the ones they can lean the most on in terms of support in battle.
And that's absolutely not a bad thing in any way for any reasonable Zoro fan.
This is another peak example of portrayal Zoro receives as Luffy's First Mate, and hopefuly one that cuts deep into the numbers of those that continued to deny him being without question the closest thing to that in the Straw Hat crew.
Absolutely amazing for Zoro's character to be the one Straw Hat at Luffy's side for the 1000th One Piece chapter, and fitting as the first person to embark alongside him on this journey :cheers: