This is incorrect
Post-Namek Goku = Trunks > Namek Goku
We know two things
- Trunks and Post-Namek Goku are relative because it's literally stated
- Post-Namek Goku got significantly stronger from Yardrat training
In terms of an overall scale it would be
Trunks = Post-Namek Goku > Mecha Frieza >= Namek Goku
But given Frieza's own statement, I'd be more inclined to believe the ">" than the ">="