Did Supremes embolden TSA?

Perhaps the Supreme Court emboldened the TSA to order Amtrak personnel, starting November 1, 2004, to randomly check IDs on board trains. I'm thinking back to this June 2004 story:

The Supreme Court on Monday upheld a state law that makes it a crime to
refuse to tell the police one's name when stopped for suspicious behavior.

Or is it possible that the Supremes now would have to throw out the TSA Amtrak directive as unconstitutional under the fourth amendment, because there's no supicious behavior test, just random checks?

This Amtrak mess should be a cause celibre for the Libertarian Party, but they're strangely silent on the issue.