But does it start the discussion off on the entirely wrong foot? If Putin endorses Dugin's book, requiring the military academies to read it, don't we have fairly high confidence that it is at least close to Putin's position?

So I don't think it's the entirely wrong foot. It's a shortcut and an imprecision, but the point (that Putin actually thinks this) seems to be valid. (Though one should have less than 100% certainty that it represents his position - but with Putin, that should apply to a direct quote as well.)

The statement should be "he endorses XZY who/which argues for reforming the USSR by force" or something. I think factual accuracy is the one thing we need to hold ourselves to, to the best of our abilities, also to ensure that we don't create an echo chamber and can keep our biases in check a bit more.