Again, this is anecdotal evidence from so-called from so called logical and rational Indians. What this is, is a conspiracy theory.
"He has said this and this", and he heard that info from this and this person, who heard it from this and this person, etc. What I am talking is the reliability of these sources, who get their info from other sources, and those sources get info from other sources, etc. They were wrong before, so that throws their credibility into question. And that's besides the fact that even if they were right before, it doesn't exempt them from providing evidence.
Btw, I am sure many things have been said before by other people who no one from US administration denied.
Did they deny that CIA is supporting terrorism in Pakistan after Pasha gave them evidence that CIA was indeed supporting terrorism maybe a year or two ago? I don't think they did. I believe they never denied Iran's accusation about supporting terrorism in Iran. Did they deny the WikiLeaks leak?
If US has said already that they believe ISI was not involved, then they need to say absolutely nothing on this. The only time they may say something is when they're asked to comment on it. Same goes for Pasha. They're not going to do a press conference just on the allegations in a book, unless it's something too big. That's how its normally done.
These are just a few examples. How come you're assuming that just because no one's denying it, that it means he must be right? Where is the logic and rationality, again?
I like how you put things this way:
Arguing that the events described in the book are not accurate is made more difficult in the absence of anyone quoted disclaiming it.
So in other words, his claims must be disproven - he doesn't have to prove his claims. Kind of illogical, no?
This part of the book DOES rely on what Pasha allegedly said. And most likely, that info was passed on from several sources up to woodward, which is a clssic case of how rumours spread.