It may or may not be unconstitutional, but the people who conceived and wrote the constitution would vomit in outrage upon learning of its existence and barely-bridled, unelected, wide ranging power.
Indeed. Hearing that the FTC plans to unilaterally modify millions of contracts to invalidate non-competes gave me mixed feelings. Those non-competes are mostly ridiculous - the products of over-zealous lawyers applying to all employees terms that may have made sense only in extremely limited cases like where employees have access to internal trade secrets and take them to direct competitors. But such major structural changes should be made by congress via legislation, not by an unelected bureaucracy that reports to no one.
Given the Roberts Court's inclinations, this argument is probably too early rather than wrong. We'll see with the Axon case noted in the article, or when some state AG sues the FTC over its proposed ban on non-competes.