I agree with you. And I don't for a second think Joe Scarborough has no idea whether his mom died in 2017, 2018, or 2019.If somebody were to ask me in a deposition or at any other time regardless of stress level, I would respond with "Jan. 28, 2018". That day is forever ingrained in my memory, as it would be for my mother, my wife, or any of my children.
I think we need to see the transcript of the Bien interview (or hear the recording). If Biden was actually trying to remember and had no idea when his son died, there is no way to defend that. On the other hand, if it was one question and he flippantly responded that he could not recall (which is a typical response in a deposition) then the report might be an unfair characterization.