On April 25, 2022, Prime Minister Trudeau selected Rouleau to be the commissioner of the Public Order Emergency Commission inquiry into the invocation of the Emergencies Act, which had occurred in response to the 2022 Canada convoy protest.

~ https://en.wikipedia.org/wiki/Paul_Rouleau

That is one step removed from Trudeau investigating himself, we're not talking the gold standard of systemic independence here.

Each political side loves laws like this until the other side gets in power.

That's the bigger picture problem with Canada (and nearly every place else). Our laws assume the government is the good guy, when they should be assuming the government is public enemy number one.

And in the Canadian system, are appointed commissions or judicial rulings supreme and overriding over the other?

In common law systems it is part of government review and is not meant to be a ruling on events already happened.

That sounds a bit like "The police carefully investigated themselves and firmly established that no abuse or wrongdoing took place".

I've read this comment multiple times and now I'm greatly confused because it does not appear to be meant humorously.

At some point in history it was legal to own slaves ...

The law is a tool for the service of a community, not the other way around.