Interesting. If the CRA was remotely competent, I expect them to work with politicians to have a better system in place at death to avoid missing tons of revenue that was due. That may cause more delays for people dealing with estates.
Why was CRA evaluating tax owed four years after death? That ship has sailed. The person is dead, the estate is closed, it's over. While I think the Jordan decision caused a lot of issues, a similar decision for the CRA seems reasonable. If you don't speak up within six months of final tax filing, it's over, don't waste money doing the investigation.