I'd prefer a rule that errs on the side of being a bit onerous to an honest President than one that gives a corrupt President a larger patch of gray in which to operate corruptly and get away with something.

But you can see why reasonable minds might disagree on that calculus.

And again, there's the problem with Congress specifically using criminal law as a bludgeon to limit Presidential authority. A law that makes it a felony for the President to pardon someone without getting the consent of the Speaker of the House would be easy to get an indictment on. The law would be unambiguous, the President's violation would be undisputed, and the constitutionality of the law is not something that either the prosecutor or the grand jury is required to consider. A civil law providing for that is very easy for the President to ignore, and there's no consequence if it actually gets upheld and he's found later to have violated it (he's immune from civil penalties and the undoing of the pardons wouldn't affect him personally). A criminal law, though, exposes him to having to mount a serious criminal defense even if its unconstitutional, and he runs the risk of spending the rest of his life in jail if a court upholds it.