Key word is 'alleged.' He is not making the accustation. He's trying to suggest that others have made that accusation . . . . to answer your question.
But he misses the point entirely. So entirely I can only think its some kind of effort to cause us to look at something that can be explained, as opposed to that which cannot.
I think it all comes down to integrity. . . . not just journalistic. Though that counts (see the author's own quote "Kristol is a political operator." What makes him stand out as a poor choice is the appearance that his self-interest (to be someone who controls others, gets attention, misleads to his own advantage) is far more motivating to him than any legacy as a great observer, communicator, analyst or humanitarian.
And I stand among those who think the Times could, and should, do better. The media in the U.S. (my vantage point is presently in Europe, reading and listening to news in other languages) can't see the forest through the trees. They fear that sales will slow to a halt and they will have to shut down. So they are all going the way of the t.v. talk show hosts who digressed to the point of inviting emotional rants onto their programs.
Very sad and, frankly, scarey.
As far as William Safire goes. He was one of the main factors pushing me toward OTHER points of view. His bias was so clear, he was so full of contempt, and, frankly, illogical and unconvincing, that I found myself seeking out opinions other than his own. That is not a vote for keeping Kristol employed (let him try to convince another resource to hire him). Rather, I say that only to calm the nerves of those who are so incensed that they can't get passed it.
Any reader worth their weight in potatoes will look for multiple sources to find versions of the truth they can believe (and if you don't, you should).
Them's my thoughts.