Pitcher of Record if rotation set for game?

[hounds33]

There was a recent 9 inning college baseball game that was played with a set rotation for the pitching staff. The starter went 2 innings, the next pitcher went 2, the next pitcher went 3, the last two pitchers went an inning a piece. The official scorer at the school gave the win to the starter since the pitching rotation was preset before the game began. I looked all over for the ruling on this, but couldn't find anything. Does anyone know about this rule? I thought the starter had to go 5 regardless.

Thanks for the help!!