What you don't know is specifically how the cameras were handled. We know they're not waterproof. That means the specifics of how non-waterproof cameras were handled in a salt-water environment makes all the difference in the world.
I agree we can't assume they were all subjected to identical conditions, but unless all 6 5Diis got dunked in salt water while every other body on the trip didn't, I think it's fair to assume all cameras on the boat received similar treatment/conditions unless told otherwise. If they dropped them in a drink, I would assume the report would have said that. The fact they point out it was an issue with JUST 5Diis w/o saying they were handled differently hints that all bodies on the trip were similarly treated.
Obviously they were used by different shooters, but those shooters then switched to backup bodies w/o issues... So what, they shot their 5Diis "wrong" in crappy conditions, then continued on with their other non sealed canon bodies also shooting "wrong" w/o having issues because of the weather?
we're both making assumptions here, but I feel mine are far more valid than yours. Clearly 6 bodies going down, ALL being 5Diis, hints that the issue is with the 5Dii in those conditions. Not JUST those particular shooters, not just those conditions. Sure, maybe all 3 were needed, but those shooters did keep shooting w/o issues with other cameras.
w/o being there I think I'll choose to assume it was the camera/weather combo with some help of the shooter. But since I own this particular body, shoot in what I consider the same conditions if not worse (and have with a 5D) I'd like to know if it is something they're entirely responsible for (but then why would canon fix it for free considering they have a very strict drowned camera policy?) or if it's the camera or what. Basically, do I need to baby my 5Dii, sell it for something else, or not worry about it?
no, there were 3 other 5Dii failures, and those were not owned by the guys who used rain covers and brought them out as soon as they got on the boat... Maybe they did, maybe they didn't. But you're making the presumption that these 5Dii owners were the only people that handle cameras in such a way they drown them. Who's assumption is more valid? Mine that the cameras would see similar conditions when in the same location with a bunch of average shooters, or yours that these 6 owners are the issue, yet canon offered to fix the bodies for free?
Canon seems to at least feel it's the camera, not the shooters. 
I've shot in "worse" weather than the LL trip, NO ISSUES.


