This is important for OPTICS. Necessary to undercut the Dems from pursuing impeachment 2.0 over influencing the DOJ in the Stone case. Barr needed to establish a "rift" between Trump and himself so that there is no appearance that Trump was influencing him. Doesn't mean Barr is a bad guy, actually he's helping POTUS with this statement by giving the appearance that Barr is working seperately from POTUS and perhaps there's even some animosity there.