"super huge" referring primarily to the 24"+ BROAD designs. It's a referential descriptor, though, since they're only really "super huge" compared to what North Americans are accustomed to seeing (namely mostly 14"-18" machetes) But generally sheaths aren't commonly used on the large models since, as mentioned, they're often "working" patterns and not used in situations where a sheath would be an advantage. Machetes are commonplace tools down there so folks don't bat an eye at them being carried around unsheathed, contrary to the way folks in our neck of the woods do.
At least that's how I understand it. If someone with more first-hand experience on the matter than I can chime in, please do. Either way sheaths for those patterns aren't common in production manufacture. When sheathed they're usually made by local craftspersons.