The only thing I can figure, pertaining to the bike veering left...is the fuel selector on all the Ninjas and FZRs I've had are on the left. If the engine sputters out, just normal reaction is to either sit up and/or lean left to check the fuel selector is "ON" or, if low on gas, switch it to "Reserve". (under the tank)
My (uneducated) guess is engine sputtered, leaned left to check the fuel was on, or move it to reserve..OR glance at the fuel hose...got distracted, veered left (from leaning that way) and thus the accident. Again, just a guess