Perhaps the engineer in question is a Chinese citizen, or immigrant from China who still has strong ties to their homeland. Maybe they think it was right to remove the Taiwan flag, and has been quietly annoyed for years that it'd still been there.

Or, hell, maybe the person is an American citizen, not even of Chinese descent, and agrees with the PRC's stance on Taiwan.

(Frankly I probably wouldn't get along with someone like this, but at a company the size of Apple, there are bound to be more than a few.)