Agreed, I can't imagine much scientific/engineering value that NASA would get from restarting the SR-71A by itself. There's an easier way to simulate the Blackbird's flight characteristics without having to magic the damn thing back into the sky.
I reckon it's much more likely to be used as part of a training program (maybe related to the shiny new F-47?) or for destructive/non-flight testing and research.
Back in the 1990s, SWRI had access to one of the operational SR-71s in order to test satellites before launch. At the time, vacuum chambers left enough air inside them that bolting the satellite inside the nosecone and flying it at 85,000 feet in an aircraft that cost about $200,000/hour to fly was a better test to ensure that the satellite will survive/operate in space.
I reckon it's much more likely to be used as part of a training program (maybe related to the shiny new F-47?) or for destructive/non-flight testing and research.