Nothing changed regarding massage. Opening in stage 3 doesn't provide any additional proof to the police regarding illegal activities, it just narrows the list of shops they will pay attention to regarding illegal prostitution. But the police already know which shops they want to target.
The cops will have more success hurting owners of illegal brothels via the COVID19 regulations. Shops in breach of these regs will face a $9000 fine, as opposed to the $1500 fine for prostitution.