Willison was on Monday morning hit with a grade-one dangerous contact charge, but crucially can pay a $1000 fine and be cleared to face Melbourne on Sunday.
The Broncos prop had placed his availability in jeopardy when he was the third man into a tackle on Garner, and hit the Panthers forward below.
Garner went to ground immediately, and the NRL has come down hard on similar tackles this year given the significant risk of injury.
But Garner was able to stay on the field, potentially aiding Willison's course given the NRL does take injuries into account when determining grading.
Willison's lesser charge will come as a massive relief to Brisbane, given the role he played on return from a broken arm in Sunday's upset win over Penrith.
The 23-year-old's impact off the bench means Brisbane always have a powerful middle on the field, with Payne Haas starting.
Brisbane's pack will also now be at full strength for Sunday's decider, with lock Pat Carrigan returning from his own suspension.
Meanwhile Penrith star Liam Martin was also handed a $1000 fine by the NRL judiciary for a contrary conduct charge, following his role in a fight with Ezra Mam.