Well, it's almost allways a matter of losing control.
In this case, even a bug could lead to an accident.
There is evidence of braking. A second impact. But the bike remained upright until it hit the verge."
1st-
I collided with a dog once, it suddenly ran out of the scrubs and hit the bike at an oblique angle from the front. I was doing about 60 mph and it all happened so fast I could'n react otherwise than clinging to the bars.
(no braking)
the bike hardly reacted and I saw the dog spinning away in my mirror.
2nd-
a friend of mine hit a (small size) deer with his Honda, going pretty fast, te deer practically exploded into two pieces, he managed to keep the bike upright, but it was a total loss nonetheless. bent wheel, bent yokes and suspension. shattered lights.
Both of these accidents happened so fast we didn't have time for the dreaded "survival reactions" like braking violently, this way the bike can regain its stability and stay upright.