More likley than not, old age. Even if it was a predator it was most likely that the ram's teeth were gone and couldnt eat enough to have enough strength to avoid predators. A ram that large is VERY old. For a wild sheep to make it past 8-9 years is a good life. If t hey make it to 11-13 theyre gods of the sheep world. From looking at that ram I would guess he was VERY VERY old.
The ram was found dead in Alberta near the Cadomine mine. Same place the current World Record was killed. Preliminary score is 206 which should put him at #8 all time. Here's another picture that shows his mass well...
If I had to guess I would guess it came out of Jasper Park as the adjoining legal to hunt areas such as Wilmoore Wilderness area haven't booted out any rams like that for decades. What a super ram!