Yes, he is. In his column today he expresses his anger over a bill that would apply the same sales tax to Internet sales that people pay now when they go to their corner store. He scoffs;
"In a burst of the bipartisanship we are told to revere, a coalition of Republican and Democratic senators rose above party differences last week to affirm class solidarity. They moved toward a tax increase of at least $22 billion to benefit the political class at the state and local levels."
Let's see, that political class would be people like Rick Perry, the governor of Texas, and Jerry Brown, the governor of California. The class solidarity here is less than obvious. It's certainly less visible than George Will's class solidarity with rich people, including those who make their money by gaming the tax code instead of doing anything productive, as is the issue here.
The sales tax is regressive. It would be great to see it replaced with income taxes. It's not going to happen whether or not we tax Internet sales. Taxing Internet sales makes the sales tax less regressive because low income people buy less of their stuff on the Internet than high income people. This is simple -- whine away, but the story is really really simple. If you want to make the tax system less regressive and you want to make the economy more efficient (why would we subsidize Internet sales at the expense of brick and mortar stores?), then you support having Internet sales subject to state sales taxes.