How does he dare to, it's a hell of risk to ride with such a camera.

 a while ago there was this dude, who strapped his 5D to Andrew Taylor's chest and let him huck the hell out of A-Line
www.pinkbike.com/photo/7285742

So this is child's play

 Some companies make bags specifically to protect cameras whilst riding. Dakine does a few.

 yeah, so does f-stop gear, I've modified my back opening Salewa with removed back protector, works fine with small and medium ICUs, but my gear is smaller and lighter (most of the time).

1D + 24-70 is 2.5kg not to mention extra gear, that's also massive volume.
Check out the guys in the shot, they carry water, some bars and a multi tool at most

Mark needs to be twice as fit to lug that around all day., I guess that's the life of the photographer...

 I have the F-Stop Satori EXP and it fits my 7D, 70-200, 24-105, and 11-16 with lots of room for other things

 clikelite.com/products/product-category/backpacks