Of course there were some Buddhists who cooperated with Mohammad Bin Qasim's invasion.But if you take a broader perspective of period between 712 AD and 1947 AD, you will find that inspite of their series of attacks, they were supreme only in some parts like what forms Pakistan of the present day.Even in Lahore, so called heart of Pakistan, there were 40% Hindus and Sikhs before partition.So their supremacy was not complete in any respect.Moreover Mohammad Bin Qasim's invasion was the first successful Muslim invasion of India but even before his invasion, there were some invasions since 670 AD. For more information, refer to Sitaram Goel's book (http://voi.org/books/hhrmi/). More information on resilience of Hindus can be found in Savarkar's book 'Six glorious epochs in Indian history'.
It is wrong to say that Hinduism 'screwed up' Buddhism and other religions.Adi Shankaracharya rejuvinated Hinduism but he did so by adopting intellectual means of discussions and persuation and not sword like Muslims.So rejuvination of Hinduism and barbarism of Muslims cannot be compared.
