> He just didn't like the font so he ordered it to be changed.

There is your answer. He imposed his will - that's what dictators do. You have to be careful when the reason for any costly change is one individual's personal preferences. It's a bad omen.

> Equivalent to your boss ordering tabs be used instead of spaces.

That's not always equivalent, especially if it is to set a standard. Obviously, some people using spaces and the others using tabs is not ideal in situations you're referring to. It's also fine to change the standard, if they find a significant problem with the current convention. But if your boss wants it changed, and their only explanation is their dislike of the status-quo, then that's a red flag. The problem isn't very serious right now, but could grow into one in the future and you have to be on the watch.