Because Gowdry was abusing the investigation process regarding Hillary for political ends doesn't make him wrong here. Investigations shouldn't take any longer than needed as a general principle. However the whole "outside counsel" process should be under the control of the Judicial branch for reasons of depoliticizing it.
The fact that Gowdy unprofessionally abused his powers of office for partisan purposes in the past doesn’t make him wrong here, you’re right. It does mean that we probably shouldn’t presume good faith in his statements though.
What makes Gowdy wrong are the obvious merits of the argument (or more clearly the total lack of merit of his). Mueller’s investigation has not gone on long at all by the standards of special prosecutors, especially not for counterintelligence investigations, and he is investigating potentially the most serious criminal case in the history of the country. In addition, this investigation has already yielded almost 30 indictments, showing that it is performing a valuable function for the country. If it needs to go on for the next two (or six) years then so be it. Gowdy should sit down and shut up.
If anything there’s a decent argument for expanding the investigation to members of Congress such as Devin Nunes.
