Grn, I'm very interested in your analysis, this kind of information might help save one of us someday. Keith Code in Twist of the Wrist I and II focuses heavily on identifying sources of target fixation that trigger survival reactions or SRs as he calls them. There's something like ten total. The reason I bring this up, I was doing my favorite ride awhile back, a long flowing stretch of 70 mph sweepers, when I went into an uncharacteristic panic state on a left hand turn I've done a hundred times. I got a perception of excess speed right before I turned in, I think that is number one on Code's list. Instead of driving it down into a deep lean, I panicked, chopped throttle, grabbed a handful of brake and even put my left foot out in front dirt bike style. Classic survival mode stuff that can get you into a serious accident or worse. Luckily I made the turn but it had me shaking. The rest of the ride I was tight, not a fun way to ride. Later on the return trip, I rolled into a hard right hander again about 70 mph and my peripheral picked up a target, a farm truck on a side road at the apex. I started to go into target fixation mode again and almost blew my line. Turns out the truck was actually parked in somebodies front yard right at the corner and was no threat at all.
I'm trying to develop strategies to deal with this and one way is to back off well ahead if you see approaching traffic in a turn.
I think you nailed it, you most likely entered that turn a bit hot which narrowed your available line options, the laws of physics at work. The truck you probably perceived as a threat and moved away towards the shoulder where the decreasing radius caught you out. You ran wide and caught the gravel or pavement drop off on the shoulder. Decreasing radius turns are scary unless you have the turn down cold. The Widomaker just west of Sanger, Texas on FM 455 has claimed seven sportbike riders lives to date as it is both decreasing radius and severely off camber, a really bad combination.
Well the important thing is you survived and will live to ride another day. Get back in the saddle as soon as you can and re-engage bro.