I have no recollection of this call so I'm not much help. Chop blocks usually aren't very subjective. Most of the time, they are the result of miscommunication. When I have one, one lineman usually looks at the other and says something like "you weren't supposed to cut him, that was my guy." I've never had a situation where the offense intentionally chop blocked a defender to hurt them.
The exception to that was when the high school rule required the second block to be delayed. At the time, you could legally high low someone simultaneously! I had a game where 3 players from one team left with major injuries because they were high-lowed legally. I submitted a rule change request to our state commissioner that night. I have no idea if my request was the one that was submitted to the NFHS. The change was implemented the next year.
The NFL rule is even more liberal. If one blocker fronts a guy as if he's going to block him high and someone else cuts him, they have committed a chop block.
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