It's just that Khlevniuk seems to agree on the factual things mentioned in the books. So do other sources I look up. And this particular book is very highly regarded as far as I can tell. They do all paint a very clear picture if you ask me.
It's absolutely important to vet your sources but usually so you know to expect some factual errors. If there's something erroneous in the book related to his description of the Stalinist state and Stalin's position in it, you should definitely point it out.
Additionally, he wrote your quoted texts from before Soviet Archives became public.
The revised 3rd edition is from 2003. It does note in the foreword "Since the second edition of this book, there has been an explosion of published materials. Very revealing are the documents which permit a greater insight into the day-to-day decision making of the Stalinist state." Haven't checked if the chapter is unchanged in the 4th edition.
It's just happens that his opinions seem to largely shared by other works about Soviet Union during Stalin. Such as the other book mentioned. It seems to be more fastidious with sourcing the claims too, so it might be more to your liking in that respect.
I wonder why books published by an Anticommunist country that went through a decades long scare would have anticommunist grifters with anticommunist opinions. I am also curious why said anticommunists also happen to be islamophobic, pro-NATO, Zionist, pro-Imperialism, and have ties to the Military Industrial Complex.
I was under the impression it was the claims we were discussing, which Khlevniuk's book seem to support, not what or who deserves our respect. For that reason it might be worthwhile to check that out too. Totally up to you of course.
Respect, as in accept the opinions. Nothing you have shown has supported the idea that Stalin could not be opposed, and was not opposed, nor that he was all-powerful.