To be fair, it's only in 70 theatres. To make 2.5M in 70 theatres is phenomenal. It's 4-5X what would be considered good. That being said, those theatres are in hmostly urbadn areas and gay friendly places like NYC, LA, and San Francisco. I don't know how well it will do in wider release. But I don't think it can be called a failure just yet.
You assume that if the movie was in 700 screens, it would make 10 times the money. I doubt it. The 70 screens were carefully picked-in areas where democgraphics support this type of movie. If the Hollywood crowd thought this movie had universal appeal, it would be everywhere. The movie doesn't; it would fail miserably in most venues.
If they run it in the homosexual friendly places first, they are bound to generate more profits initially. Using this they can say,
"Look the movie did really well at release. Better than expected. You should see it too!"
It's all propanganda.