why are Indian muslims such 'nationalists'?

Not true, either factually or rhetorically.

Best muslims are those who practice Islam to the fullest, the rest are aspiring, or half, or muslims by names and they're all found everywhere. The earth is wide and spread. Some of the best muslims maybe found in Africa, America, Australia, even in the middle of nowhere. It's not inclusive to Pakistan or India or Asia alone for that matter.

Blind patriotism is not a good thing; just as painting everyone with the same brush isn't. :)