Broadbent joined Featherstone Rovers on Monday, on a loan deal lasting until the end of this season.
He is out of contract this autumn and expected to sign for Castleford Tigers.
Speaking at his weekly press conference on Tuesday, Smith said Broadbent's decision to leave was made before he took over as coach.
"Jack is moving on next season," Smith stated.
"He was looking for some regular game time and I couldn't give him that with any confidence in the next month or so.
"There was an opportunity for him to go and play at a strong club [Rovers] so his request was granted there."