Basically trying to say please stop tweeting as you are making my job of giving you and your criminal friends cover more difficult. Barr is a disgrace to the job he holds. He isn't the peoples lawyer he's Trump personal and political lawyer. This statement is him just giving himself and GOP representatives cover.
Given it appears as though it is mission accomplished as far as Biden is concerned, given recent polls, this Barr tweet is more about Barr pleading with Trump not to spoil the ABSOLUTELY CERTAIN investigations that are being planned by Barr and DoJ into Bloomberg, Sanders, Buttigieg *and* their close family members, by tweeting openly about it, until the time is right. The plan will be for investigations to be announced at the appropriate time, say a couple of months before the election, and for Trump to feign mock surprise about the revelations at that time for maximum effect. Trump tweeting about going easy on friends, or hard on enemies, like this now makes it harder for Barr to claim the investigations are legitimate and not politically motivated further down the line.