I know why this particular book is doing circles among Pakistanis. Because that's the only one that shows Pakistan in somewhat of a good light, or let's put it like less worse, gives you a chance to breath with ease for a moment. But, no matter what it says, it does not hold the tiniest bit of flag in front the assessments and survey done by Bangladeshi government. Reason ? they did that when it actually happened not after 40 years and is not based on random interviews of people who may or may not even had been there. A sexagenarian living in the 70s in Dhaka will know better than a sexagenarian of today who was a teenager back then.
So, buy the book, help the author, it is targeted at audiences like you only. But don't expect World in general or Bangladeshi government in particular will buy what it has to say.