This is the latest in a long string of similar phenomena over the last decade or so, as we see patriotic loyalty (or the lack thereof) becoming a political issue in the context of offshoring, globalization, outsourcing, and so on.
A response to the charge of being unpatriotic would seem to me to require at least two points.
First, the responsibilities of a business owner, CEO, or corporate board are different than those of a government politician. They have different loyalties, so to speak. So to judge the one by the standards of the other is an exercise in missing the point.
Second, I would respond with a query along these lines: Which is more unpatriotic, a greater disservice to a nation, for someone to be involved in: moving a business from one country to another or making the tax environment in a country inhospitable to businesses?