Although I would disagree with all the conclusions, overall I think the OP was a nice article. It goes into details of why Indian kings lost without resorting to excuses like 'They followed rules of wars' and what not. I don't think this passiveness is a Hindu phenomenon alone, IMO even later Mughals (who were completely Indianized) showed the same weakness that are shown by earlier Hindu Kings. So this is a Indian problem not just a Hindu problem.
Some reasons like 'India was rich that's why we didn't attack any one' isn't very true. India was never a single country so the economy of the entire country should not be taken into account. Saying India was a large economy is like saying Asia is the largest economy in the world today. There have also be empires like Rome, Persia and others who despite having a huge economy continued to expand their territory. Comparatively most (not all) Indian kingdoms would have had only a fraction of their wealth, yet they never found the need to expand their territory and wealth.
There is also another example to show that India was an exception, lets look at large continuous areas of settled populace around the world. There are a few major regions like Middle east, Europe, China and India. All the other regions had large empires that controlled them.
Middle east had Persia, Safavids and Several Caliphates
Europe had Rome for a large part of its history
China had several Chinese Dynasties Like Ming and Qing
India OTOH had none, expect for a breif period under Mauryas. Its not just that India never had an empire, but it seems nobody in India even tried.
We can count with one hand, the number of aggressive Indian empires, Mauryans under Chandragupta, Cholas, Vijayanagar (in early years) and Marathas are all I can think of. Rest of the kingdoms seems pretty content with ruling over their land and fighting small border skirmishes.
Nobody can say the exact reason for this attitude, may be it is the lack of killer instincts or may be there is some other factor, like caste system preventing mobilisation of a large standing army. Whatever the reason India's lack of large empires ended up making the country highly vulnerable to outside invasions