The rules don't really apply for non-profit productions like they do for commercial productions. Simply put, while the show might not be making money with grosses like that (although it is good to bear in mind that salaries are also lower at non-profits), MTC has already set aside the money to finance this production through its scheduled run. So, while the show may not be doing terribly well, it's not really in danger of closing due to a low gross. Also, shows at non-profit theatres tend to have lower profit margins anyway because those theatres rely on a subscriber base that almost always pays less for their tickets.
I am a firm believer in serendipity- all the random pieces coming together in one wonderful moment, when suddenly you see what their purpose was all along.