Forget all of the many large ways in which this comparison is silly. There is one small, but very telling difference: Nearly everyone who knows Blumenthal--even his political allies--despises him. Nearly everyone who knows Hewitt--even his political adversaries--likes him.
If you're the type of person who thinks that character counts, then it's impossible not to number Hewitt as one of the good guys, regardless of his (or your) politics.
Update, Sat., 12:14 p.m.: Power Line has a list of reasons why the comparison of Hewitt to Blumenthal is ridiculous. A commenter here has something else to add:
If Hewitt is to Bush as Blumenthal was to Clinton, may I propose that Sully is to Bush as Bill Bennet was to Clinton?
That is to say, a humorless self-righteous prick who is quite certain he's never been wrong about anything. Ever.