I agree that consistently staying late as a way to stand out could be seen as a dick move. However, it is also the management's job to evaluate the employees' performance based on their quality of work, not how long they spend in the office-- that is just lazy.

I agree with your definition of work ethic. It is just the way people work; How they feel responsible towards their work., how they are being considerate co-workers, and so on. However, I do not think the writer sees working late as a favourable work ethic. His approval of Alex's quality of work and dedication does not mean he directly encouraged him to work late for such results.

People have choices to do what they want with time and energy. As long as the intention is fair, why should anyone be bothered?

If I were Alex's colleague or manager, my concern would be placed on Alex/Ithipol's well-being, not pointing a finger at him as a person who makes others look bad or question his work ethic.