Pre-inning team meeting on the mound

[DaNewGuy]

In a recent 12U tournament, one team began every defensive half of the inning by gathering all 11 players and 2 batgirls (ages 7 and 9) at the pitcher's mound. They all knelt down and conducted a cheer of sorts while pounding the ground. The two umpires (I was spectator only) are two of the senior umps in our organization - they allowed this every inning. A number of spectators, including coaches of other teams in the tourny said this was illegal. Opionions and applicable rules?