What an adventure!
I wasn't there, so I will NOT presume to second-guess the actual participants regarding the clutch failure. The KLR650s (at least the earlier models; I think latter-day ones lost a couple of disks) have extraordinarily robust clutches; failure/malfunction rate low, given correct operation. My theory . . . the current population remains basically unfamiliar with manual clutch operation; FEW automobiles have "standard transmissions" with manual clutches . . . the KLR clutch is NOT analogous to an automatic transmission, the latter delivering power through a fluid coupling.
If a manual clutch is slipped excessively, it WILL fail. Choosing lower gears when appropriate, and slipping the clutch minimally (preferably, only at start-up) extends clutch life.
All this said, from the looks of the clutch disks in the images from the blog, that clutch was a textbook candidate for the, shim-up-the-clutch-springs field expedient to extend its life. Maybe these adventurers tried that approach, but . . . no mention of any such attempt in the text I read from the link posted.
The sacrifice of a KLR for such an expedition isn't a particularly great price to pay, IMHO; the bike might have been saved, but . . . as previously mentioned, I wasn't there; any such suggestion remains total conjecture on my part.
Congratulations to the party on their success!