Your best bet in this is to accept the Indian point of view completely, and that is that there was not, in ancient times, any such thing as Buddhism ~ just another branch of Hinduism.
Which, of course, begs the question of what was going on in the 5th and 6th century that required such militant action on the part of the Hindus.
Wow! You really go out of your way to avoid facts, accuracy and substance. Not one of my five links was from Wikipedia.
The decline of Buddhism is not in dispute here. The Muslim conquest of India nearly wiped it out completely. I'm sure that Buddhists and Hindus alike found what opportunities they could to rectify that. Who could blame them? No sane religion is a suicide pact.