Since when - - - ?
In those days did the US turn down a challenge because it would lose money? Remember the Moon? ICBMs - 10 times more than necessary? The list goes on.
It was completely uncharacteristic for the US to abandon the SST. My friends story passes the smell test. Abandoning it as impractictable doesn't.
At least for my nose.
(And the guy was an honest guy with no need to make up something.)
But that's why we have opinions. Thank God.