I suspect that in his distress, he's subconsciously extended the willpower-controlled anti-gravity field generated by the Legion flight ring he has on under his glove. The field *can* be extended - Dream Girl was the first to do it consciously, in a solo backup story in the '80s.
It was established later, during the Lightning Saga, that all of the Legionnaires on that mission had mental blocks in place to prevent a telepath (i.e., Saturn Girl) from learning their true plan. It caused Karate Kid, Timber Wolf and Sensor Girl definitely to have amnesia, possibly Dawnstar too. If I'm reading Starman right in these pages, the blocks didn't fully take on him, but he didn't really remember being a 31st century Legionnaire until the last page, and wouldn't have been conscious of the ring's function.