That book? That's rampant revisionism by the author. Some people just want to deny that the Galactic Empire was undergoing an inevitable decline, and have a need to pin the blame on someone. Even during Seldon's life, there were people who referred to him as "the Raven", and who tried to imply that he was somehow acting to bring about the decline that he was merely predicting. It was a classic case of shooting the messenger. And, this modern author with his 'Foundation: A History' (which should rightly be called 'Foundation: A False History') is just buying into the same thing. He hasn't checked his sources, and he doesn't realise that he's using gossip by Seldon's contemporaries as the basis for his so-called theory.

Let's face it, if Seldon really was a raving anti-imperialist, would he have set up conditions to form a second Galactic Empire? Sure, we all know that the robot Daneel Olivaw and his catspaw Golan Trevize derailed Seldon's plans only halfway through the millennium, but the surviving evidence shows that Seldon sincerely wanted to created a second Galactic Empire - which is not the behaviour of an anti-imperialist.

That book is just the author's attempt to re-write history according to his own agenda.