I tried to find logic in it all. Then I thought about it. If Lisa weren't there, and Antonia stayed, it would be:

Antonia, Richard, Stephanie.

What do these 3 have in common? They all get along with each other! Think about the previous 3 seasons. There has always been the "villain" in the finale. Bravo doesn't want a show where everybody gets along.

Season 1: Tiffani
Season 2: Marcel
Season 3: Hung
Season 4: Lisa