I am known to award a HBP almost every time. At the HS level I have seen players jelly legged by curves, frozen by an errant fastball and even a flinch is enough for me to determine they tried to get out of the way. Its up to me to determine if he made an effort. If as you say it a clear violation such as I state below. There will be no base award. But that is Umpire judgement......and in other words "my judgement"..........backed up by my umpire education and years of experience.
For me to keep a batter at the plate he would have to basically move into a pitch. This year I kept 2 players at the plate after being hit. Both for dipping an armor padded elbow into a slow curves.