I have to agree with you. If BJP plays politics and brings down the government on this issue, then the educated and urban electorate which is BJP's constituency will desert them during elections. The Commies will get their votes anyway from the don't-care-about-development crowd but BJP will pay heavy price. Think about the times of Rajiv Gandhi. BJP and Commies were friends but Indian electorate gave massive mandate to Congress and BJP got 2 seats. The point is the supporters and sympathizers of BJP want this deal. They don't support Congress but they do support this deal. BJP should feel the pulse of these people and act accordingly. Don't make common cause with Commies.
