> The author meant this signaled a lack of character because... I dunno. It means the person wasn't as committed as the author?

It is simple. Salary has to be paid, now. The stocks is likely end up being nothing as most startups fail. So, the author is strongly motivated to pay in stock options and not pay in money.

But, admitting so would make him sound bad. Therefore, it is about your character. If you want to actually be paid, you have bad character.