First, you can't just add up breakers, that tells you nothing. If there is no information about the connected loads the NEC has formulas to calculate a loads.
Second, the 200A breaker feeding the panel is protecting the conductors and panel, so a main breaker at the panel is redundant.
He knows it needs a Main OCPD for the panel. He's talking about needing a 2nd main at a subpanel just because the ratings of the branch breakers exceed the rating of the panelboard.
Not so.
You don't count up the amperage that's printed on the face of the breakers, and, if it exceeds the panel rating throw a Main Breaker in for good measure.
