Well, this is what happens to Ilford Delta 100 when wetted for 5 minutes, dunked in meths, and set afire. Took about 3 seconds for the film base to corkscrew like this and for the flame to go out. The emulsion is lovely and dry and the image would be printable if the backing wasn't distorted. Absolutely no sign of the emulsion slipping.
I seem to recall that Delta films have a different film base to older film types like FP4/HP5, and maybe in Capa's day they were different again? All the same, no emulsion slippage.
It doesn't really matter, IMHO. Whatever the reason, it must have been gutting to have been to Hell and only have a couple of pictures to show.