I don’t think the article gives enough detail to make that case. We could torture the scenario any number of ways to arrive at whatever conclusion we’re after but the comment about weight loss being more attributable to a caloric deficits from eating less generally stands. For most people, it’s much easier to eat calories than exercise it off.

Saying someone is "wrong" then jumping into a pedantic point isn't very constructive.

Ultimately using your own figures (400 Vs. 600) it doesn't alter the person above's overarching point: That most of the weight loss was from diet changes (as is typically the case).