This move - claiming Manafort lied to Mueller's team - means Mueller's team nuked any value anything Manafort said and as a future witness. IOW, Mueller & Team got nothing they considered as having value from Manafort.
It's possible that Manafort simply told truth Mueller, et al, didn't want to hear or be heard. But where DU's [/i]Trump-Hatred[/i] is concerned, Manafort just became a big, loud, "Womp! Womp!"