TLDR: PBO issued a report (due to an "error") that suggested carbon pricing has a negative economic impact than doing nothing. This error was discovered by third party experts and public critics only upon its release. The premise of "doing nothing" having lower economic costs is false because increased carbon emissions have economic costs, and Canada in breach of global carbon reduction agreements it signed up to has trade and economic costs. None of which PBO accounted for in its erroneous analysis. PBO further states that the government has its own analysis of carbon pricing but he doesn't have the authority to release it.
This sounds to me like PBO is sabotaging the government on this policy issue, 1st by attempting to show that carbon pricing had negative economic impact, and 2nd by suggesting government is withholding its own analysis.