Another Warriors losing effort - their fourth in a row, and eighth in 12 starts as the halfway point of the season arrives - saw Montoya clock Newcastle winger Dominic Young high in the middle of the second half.
While criticised by fans at the time, the shot saw him placed in the sin bin for ten minutes.
The incident saw Young quite low, however, it was ruled that Montoya had plenty of time to adjust in an attempt to avoid hitting Young in the head, which he failed to do.
Despite being hit high, Young wasn't forced off for a head injury assessment, and completed the game, although failed to cross the try line for the Knights in their eventual 24 points to 16 win.
The charge, under the NRL's new judiciary code, will see Montoya face a fine of $1800 with an early guilty plea, or $2500 if he fights at the judiciary and loses, which he is unlikely to do.
The charge also means Montoya will walk a tightrope for the remainder of the year, with penalties for third offences and beyond within a 12-month rolling window leading to higher suspensions pending on the nature of the offence.
While some minor offences can still be escaped with fines, suspensions for other offences can be as many as six weeks for Grade 3 slip ups.
There were no other charges out of Saturday's games, with the match review committee releasing their findings on Saturday morning.