Not a foul. It might not be sportsmanlike, but it does not rise to the level of Unsportsmanlike Conduct.
Which code are you referencing? My 2021 NFHS Rule Book defines "Unsportsmanlike Conduct(by players- 9-5-1) as, "No player shall act in an Unsportsmanlike manner
ONCE THE GAME OFFICIALS ASSUME AUTHORITY FOR THE CONTEST. Subsections A & F seem to contradict your conclusion. NFHS 9-8-1 USC by NonPlayers seems to share similar intent (supported by Subsection examples A(Note).
Of course how each of us interprets & understands these rules is our
own personal decision. However establishing, and subsequently maintaining a civil & appropriate competitive attitude is a major officiating objective. Allowing any sort of Unsportsmanlike conduct, or behavior is a primary responsibility of the Game Officials and allowing
ANY such behavior by participants and/or supervising staff is a recipe for encouraging additional such behavior.
That choice is determined by the Officiating crew at each game, who must live with the consequences of their choice.