"Would" in a backshifted reported context

Question

In one of many amusing anecdotes, Ostrovsky recounts how in 1989 a quintessential apparatchik, Viktor Chernomyrdin, quit his ministerial post to become chairman of a new state corporation, Gazprom. The prime minister at the time, Nikolai Ryzhkov, couldn’t comprehend why he’d do this: “You understand that you will lose everything – the dacha and the privileges?” The wily Chernomyrdin suspected that the new prizes would be denominated in dollars, billions of them.

http://www.theguardian.com/books/2015/oct/05/the-invention-of-russia-the-new-tsar-the-red-web-book-reviews

Does "he'd do" here mean "he would do"? Why the rule of backshift of tense in reported speech is not used here, i.e. why the part of sentence is not: "couldn’t comprehend why he had done this".

Answer 1

The would in why he would do this is not the ordinary futurive will in the past tense, which would indicate a "future-in-past". It is volitive will—the will which indicates a willingness to do something—and the past-tense form is what CGEL calls 'modal remoteness': it expresses the doubt or perplexity which the questioner feels.

• Volitive will is illustrated in expressions like this:

  If you'll pick up some snacks, I'll get the beer. Here what is meant is 'If you are willing to take care of getting snacks, I am willing to reciprocate by providing the beer.

  That would can be used in the IF clause without any substantive change in the meaning; the past-tense form just marks a 'social' remoteness, a less demanding and therefore more courteous way of expressing the same thing:

  If you'd pick up some snacks, I'll get the beer.

  And in a different sort of context the past-tense form may mark a sense of perplexity at something which appears irrational or improbable:

  I can't understand why you would do that.

• Tense here is tricky. Would can also be used in present contexts to express counterfactuality: something that is known not to be true or not to happen.

  If wishes were horses then beggars would ride. Wishes are not horses, and beggars must walk.

  When this sort of would is moved into a past context, the backshift is accomplished with what I call a "sham perfect": a perfect form used as a past marker:

  If wishes had been horses then beggars would have ridden. (Note, by the way, the same device is used to backshift counterfactual were → had been.)

  But in cases where you backshift a past form representing a modality that falls short of full counterfactuality, like the volitive would at the end of the first bullet, the backshifted form is unchanged.

  I said that if he'd pick up some snacks, I'd get some beer.
  I couldn't understand why he would do that.

So the perplexity attributed to the Prime Minister represents a backshifted

I can't understand why you would do that = I can't understand why you are willing to forego your privileges.
→ He couldn't understand why Chernomyrdin would do that = He couldn't understand why Chernomyrdin was willing to forego his privileges

Answer 2

"Reported speech" doesn't have anything to do with the bolded part in your question.

The prime minister at the time, Nikolai Ryzhkov, couldn’t comprehend why he would do this.

I expanded the contraction to let you know that it is indeed "he would."

This is a complete sentence. The colon is a piece of punctuation used to show that the next quote clarifies or provides evidence for the author's statement in the article (the quoted sentence in this answer). The sentence and the quote following it don't have any grammatical relation; it is only contextual.

The author sets the timeframe with the phrase "at the time," and uses present tense for the rest of the statement in the original article. The prime minister is (not) comprehending at the same time that Chernomyrdin wills to "do this," so a tense shift would not be appropriate.