It is a Cover Page
Story. These have never been gags and are part of the One Piece canon.
When Hatchan escapes from Arlong Park and sets up a teriyaki shop, it is canon.
When Jinbe finds a Poneglyph and recruits Wadatsumi, it is canon.
When Enel goes to the moon, it is canon.
When Wapol creates Wapol Metal and becomes the ruler of Black Drum Kingdom, it is canon.
When Jango assisted Fullbody and became a Marine, when Bon Clay was shown to be alive, when Pound reunited with his daughters, when Axe Hand Morgan escaped Marine custody, when each Straw Hat got a cover story explaining where each of them went due to Kuma etc. etc. etc. Each and every single one of these cover stories is canon.
So when Gedatsu tanks a fall from a Sky Island with barely a headache in a cover story, that shit is canon.