So does he remember why he was going so fast before the crash?
If he listens to his lawyer then no, he won't remember that.
A locomotive’s throttle is a smallish lever; move it one way the locomotive speeds up, move it the other, it slows down. In that regard, running a locomotive is a lot like driving a car. Also, as with a car, the operator is going to get a good instinctive feel of how fast he’s going. IOW, a reasonably straightforward job in good weather. That leaves deliberate operator misconduct as the most likely explanation,followed by operator impairment, mechanical defect, and sabotage as lesser, possible, causes, all of which need to be investigated.
I find it odd that so much emphasis was made regarding his not being able to find his phone and that it was stuffed away in a bag. I guess the phone records will tell.