I mean the attorney general is supposed to be non partisan. They are not supposed to be an advocate for a political party or any particular person, including the president.
I'm not sure how true this is in practice, but yeah, it was a rather partisan speech, I'll admit. During Obama's presidency the common fear among Republicans was that the executive was too strong, for the simple reason that a member of "the other party" was running the executive at that time. Now the tables have turned, so they adjusted their behavior accordingly.
But the Mitch McConnell had been laughing and announcing that he was going to block everything under Obama and making it part of his election campaign that he would do it again if the Democrats won in 2020.
The republicans have been destroying norms and rules for years to try to block the executive branch when it wasn't controlled by them.
This isn't as true as you might think, actually. To quote Barr in his address:
"A prime example of this is the Senate’s unprecedented abuse of the advice-and-consent process. The Senate is free to exercise that power to reject unqualified nominees, but that power was never intended to allow the Senate to systematically
oppose and draw out the approval process for every appointee so as to prevent the President from building a functional government. Yet that is precisely what the Senate minority has done from his very first days in office. As of September of this year, the Senate had been forced to invoke cloture on 236
Trump nominees — each of those representing its own massive consumption of legislative time meant only to delay an inevitable confirmation. How many times was cloture invoked on nominees during President Obama’s first term? 17
"Just to summarize briefly, nationwide injunctions have no foundation in courts’ Article III jurisdiction or traditional equitable powers; they radically inflate the role of district judges, allowing any one of more than 600 individuals to singlehandedly freeze a policy nationwide...Since President Trump took office, district courts have issued over forty nationwide injunctions against the government. By comparison, during President Obama’s first two years, district courts issued a total of two nationwide injunctions against the government. Both were vacated by the Ninth Circuit."
(Keep in mind that there are plenty of district court judges who were appointed by Republicans, and there were plenty such from 2009-2017. Any one of them could've done to Obama what's being done to Trump now, but for the most part they did not exercise this power.)
He thinks that the president should be a quasi dictator.
Nope. He argues that there are certain areas that belong solely to the executive, as there are areas that belong solely to the legislature or to the judiciary. Instead of this being the case, however, in the Trump era the legislature and judiciary have moved to strip the executive of much of its traditional authority/ability to operate and function, in a fashion that's without precedent in American history.