Why does an emergency vehicle with lights and siren need to be escorted by lights and sirens??
And why does he think traffic has to be blocked when any vehicle in the universe can merge safely into traffic without having some dweeb park in front of it to make sure?
As for what was the driver looking at, he was unsighted as little as 4 seconds before impact, both by the truck and another car between himself and the truck. At least half of that 4 seconds was realizing that some dumb **** was parked in the lane in front of him, then he's checking his six and realizing he's gonna get creamed if he jams the brakes, and if he swerves then the next guy (who's now closer still) suddenly discovers the parked bike, etc. etc. All four cars behind the truck had very small following distances, and only the first had time to react and change lanes.
This is all on the LEO, and I can't for a second believe it's standard practice. You NEVER block a motorway lane without signage well up the road, big lights bright enough to be seen for several hundred yards, etc. Not something you can set up on the fly.