hit by pitch on bunt attempt?

[TwoWays]

how can the ump award first base to a guy that squares around to bunt, leaning into the pitching zone? this just happened to marte in the pitt vs. rays game. the ball thrown was not even inside enough if the batter was not attempting to bunt. wouldn't hitters just do what marte did if they wanted to get a free base?

[Big Bear]

i was always told to throw at the guys nut sack if he squares around to bunt.

its one of those unwritten rules never square around to bunt.