The problem India has - is that there is not much of value to hit in Tibet for HIMARS.. but China has its own version of HIMARs and there is alof of high value items for China to hit in India in such an exchange, as even New Delhi is in range.
If India does procure the HIMARs, it will be for Pakistan and not China.
Of course, if I were India, I would acquire it as a Pakistan-specific weapon as well. Just be ready once this conflict is done India is going on an enormous spending spree and American training, and it will come to haunt Pakistan down the road. No amount of boot licking will save it; Pakistan will be neutered.