That is true. It is the Court's job to make sure Congress (not the President, btw) didn't step outside the bounderies set by the Constitution. Since the tax argument was one of the three made by the government, he found the individual mandate to be not that much different than Social Security and Medicare (much larger taxes then this, btw again, since those cover everybody and this one only cover a small portion of society ... those irresponsible enough to let others pay for their healthcare), so his Conservative pricipals caused him to not to be an activist Jurist, unlike is political kindred who voted no.
He was forced to accept a program he probably didn't like because he was doing his job as a judge and letting the Congress and the People do their jobs as defined in the Constitution. If, the government had not made taxes as one of their arguments, I suspect he would have voted no.
I read the syllabus of the opinion had it changed my mind about the efficacy of the Commerce Clause argument, it clearly doesn't hold under his reasoning. I am still studying the Necessary and Proper Clause argument.