@Debra Law,
Yes of course, you're right. The key is "corruption" and not simply an endeavor to influence an investigation.
As McCarthy noted in his article prosecutors exercise influence on not only investigations but criminal proceedings by exercising discretion. Comey exercised discretion in relation to HRC and I'm not sure that was even within his authority, but if it is and if (as we know to be the case) the AG can exercise discretion, so can their boss. If he was urging Comey to give a good guy who has suffered enough a break that's not corrupt.
The primary difference between your argument and McCarthy's is interpretation of the facts, but that's not the lawyer's role it is the judge's or jury's. You don't have to agree with opposing counsel's arguments, but it's rarely smart to dismiss them out of hand as childish.
His opponents want to make much of everything Trump is alleged to have said if it serves their purposes but recall that Comey also testified that Trump told him that it would be good thing to uncover any collusion that his "satellites" might have engaged in with the Russians. Now that might have been because he knew Flynn was the only one to have done so on his behalf, but no one can possibly know that to be true based on what we know about this matter.
What I object to are lawyers who are offering "legal opinions" that Comey made or just about made a clear case for obstruction charges; for partisan political purposes (e.g. Lawrence Tribe) i.e. to damage the president of the United States.
On more than one occasion I've argued than citizens not directly involved in a legal proceeding are under no obligation to assume innocence until guilt is proven, but it seems to me that if someone is offering a legal opinion based on their professional education, experience and credentials they ought to at least keep it in mind until a lot more facts are known