Maybe there wasn't a male lead? The movie belonged to Jodie Foster. It is possible for a movie to not have a male lead. I guess you could call Tony Hopkins the "male lead" in The Silence of the Lambs but regardless of that, it still doesn't take away from the fact that he was a supporting character. Jodie Foster and Scott Glenn had more screentime than him.
Yes, it's possible for a movie not to have a male lead. That wasn't Silence in my opinion. Amusingly enough, the Academy agreed with me on this one---Hopkins got the Best Actor Oscar, not the Best Supporting Actor Oscar. On the other hand---
However we're arguing semantics, really.
You're right. So let's think of it as a brief off topic discussion. It's interesting in its own right. Is it more useful to go by official order or screen time? Or is it more useful to consider the importance of the role in the story or the importance of the actor in drawing an audience? The latter is more sensible in most cases but there those examples, like Silence or Beetlejuice, where it's more subjective. Which means, more confusing, not clearer.
As to box office as a selling point in Oscar campaigns---I'll defer to your experience. I do tend to avoid ads.