All they claimed was that there was no clear evidence in Bobulinski's text messages that Joe Biden was involved (though the "big guy" phrasing refering to Joe was not proved one way or the other).
It does not discredit the emails, nor Bobulinski's own testimony. It's actually just a pretty reasonable and reporting of the information they had available.
[1]https://www.wsj.com/articles/hunter-bidens-ex-business-partn...