The Met is not like a normal business, they only get about 60% of their operating budget from ticket sales, the shortfall is made up from the City, Large Donors and corporate donations.
Some of the larger jewish donors were unhappy with the opera and the other donors suddenly became anonymous. Businesses do not want to be associated with controversial things.
The Opera last night did not sell out and there are plenty of tickets for upcoming showings (You can check the Met website and verify this)
And since there is city money as well that could be in danger as well. So in the end this will directly hurt the Mets bottom line. In fact the Met almost closed due to the budget shortfall and problems in making up for it