A "deliberate act" or a reflex reaction by a driver startled and glancing behind to see what was happening? I would argue the latter.
Good thread BTW.
It can be argued either way Denis, it's just my opinion based on him being a trained driver (I assume). Why not hit the gas as a reflex? By the same token, it must have been quite an extreme situation. The result is the same, slowing down to almost walking pace at the same time JFK is hit in the head.
It should also be noted that the driver had already looked round once, continued to decelerate then looked round again before deciding to floor it. Why the second glance?
It's hard to judge as everything happens so quickly.