@revelette1,
The position of the WP editorial board on President Trump has long been one of fairly rabid opposition, and this editorial is entirely in keeping with that.
Obstruction of justice usually involves an underlying crime. In Trump's case there was none. Despite that, he was subject, throughout the two year highly political investigation, to incessant charges, ranging from a conspiracy to rig the election to treason - all of which are now known to be without foundation. Trump generally cooperated fully with Mueller's requests for information and documents, despite the obvious ruthlessness of Mueller's prosecutions of former associated for unrelated wrongdoings and all that it implied for himself. His current resistance to the now ongoing effort to resurrect the now discredited charges is both understandable and appropriate. Moreover it is entirely legal.
Though the WP editorial call's Trump's use of Executive Privilege a matter of "bad faith", there is nothing that is either unusual or unprecedented about it. The assault on the Constitution here is not by President Trump, but rather by enraged Democrat Congressional leaders : they are unable to accept the results of Mueller's investigation, and are increasingly fearful of what may emerge from the follow-on inquiries about the unsavory origins of this sad affair in the hands of Obama Administration figures, a group of now disgraced former FBI officials, and likely the Clinton campaign.
I believe the WP editors know and understand what they are doing to advance their own highly partisan position. However the unthinking credulity of some of their readers is somewhat remarkable.
That said, I believe the increasingly comical spectacle of denial and indignation on the Part of House Democrat Committee leaders (who themselves have already been proven wrong in their prior pronouncements of supposed "facts" in the matter ) will not persuade voters .