All are correct - unsportsmanlike and should not be a balk. Probably would not have ejected the player - but a warning to player and bench definitely warranted.
Similar story - doing a 9 or 10U game ... bases loaded IF popup. Infield fly called. A parent behind backstop yells "drop it". After the out - I loudly announced that whomever it was should be ashamed of themselves. Then promptly banished all spectators to the outfield fence.
Coaches from both teams thanked me.