I have used 20x2.4 tires on the Sun CR 18 rim (22.5 mm wide) and that works fine. The machete and momentum tires are not thorn resistant. The momentum is supposed to be the lightest wire bead BMX tire there is. I would like to see a lighter folding tire in 2.4, but the momentum is quite nice. I like the minimal tread vs a knobby, because of the big variety of surfaces out there on rides like the Oregon outback.
I knew there would be a difference between 2.0 and 2.4 in how the bike rides, but I did not expect it to be so big of a difference. The 2.4 is plush; I let it go faster downhills, and cornering feels very secure; theres more grip. Where I may struggle with the 2.0, the 2.4 rolls much more easily. I can roll with less pressure in the fatter tire without issues, like pinch flats.
It's not a magic carpet ride on all surfaces of course, but it leaves the 2.0 in the dust for divide-style riding. That said, you CAN use 2.0 for the divide or Oregon outback. It's just slower and more work where the riding gets rougher.