Yes, they're going after Steele, to invalidate him and his evidence. And to invalidate any other evidence that was gained by the FISA warrant, which was based on Steele's invalidated evidence. This will significantly narrow the vectors that Mueller has at his discretion to pursue the President, while also forcing Mueller to defend why he didn't invalidate Steele already, himself.
As Mueller and his investigation is weakened, and public opinion continues to be brought up to speed on the accusations against Trump which were based on the Steele dossier were improper, the weapons of law enforcement can then be better targeted on the cabal of true criminals such as Hillary and her compatriots who worked with Steele to manufacture those charges.
Bottom line this is a huge shot being landed on Mueller, and the root of his original investigation against Trump. In my opinion, of course!
Good point thanks.