I'll recycle an old post of mine:
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India using force is almost ASB territory as long as Nehru leads India in 1950-51. He was anxious to see the PRC admitted to the UN, anxious to preserve India's position as a "neutral" power that could broker a peace agreement for the Korean War, etc. Moroever, he believed that "We cannot save Tibet, as we should have liked to do, and our very attempt to save it might well bring greater trouble to it."
http://books.google.com/books?id=-5z3AwAAQBAJ&pg=PA124 (He was also worried about Pakistan taking advanatage of any India-PRC conflict.)
The only POD I can see making Indian involvement more likely would be if something happened to Nehru, and Deputy Prime Minister Vallabhbhai Patel
http://en.wikipedia.org/wiki/Vallabhbhai_Patel became Prime Minister. Patel was much more concerned over the PRC's takeover of Tibet than Nehru was; see Itty Abraham, *How India Became Territorial: Foreign Policy, Diaspora, Geopolitics* (Stanford University Press 2014), pp. 124-6 for a summary of his views. Patel observed that previously concerns over India's security had overwhelmingly focused on the Northwest, Tibet having formed a buffer on the Northeast. This buffer was now gone, and Communist views could easily be sold by the PRC in the "weak spots" of "Nepal, Bhutan, Sikkim, Darjeeling, [and] tribal Assam" bercause of serious pre-existing class and national resentments. Patel warned that "Chinese irredentism and Communist imperialism" were different from, and much more dangerous than, the imperialism of the western powers.
http://books.google.com/books?id=-5z3AwAAQBAJ&pg=PA126
But there is an obvious problem with having Patel lead India into war with the PRC on account of Tibet: His health was very poor by mid-1950, and he died on December 15, 1950...
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IMO this would still be true with an undivided India, at least as long as Nehru was the leader. Yes, the worry about Pakistan taking advantage of an Indian-Chinese war would not be applicable, but all the other reasons would still be. One shoud also remember that the Government of India, both under British rule and when indpendent, always recognized in principle that Tibet was part of China, so it would have a hard time finding legal justification for interrvening by force when a Chinnse goverment (Communist or Nationalist) was finally strong enough to make good on its claim.
