our school had a top female sprinter in washington state who walked "in-toe" and i knew at least one other track athlete who looked up to her and intentionally changed gait to walk in-toe in order to be more like the star sprinter

when im walking by people facing my direction (past a row of seats at the airport, into a movie theater, etc) i become self aware and try to walk as relaxed and invisibly as possible. probably only makes things worse. i think lots of people, autistic or not, are sensitive and adjust their gait unnaturally all the time. however toe-walking certainly seems difficult and i cant think of a reason id do it intentionally

That sounds like something a runner who knows that they have a tendency to heel-strike would do.

our sports teacher (USSR, mid-80ies) specifically instructed us to try to put feet "in-toe" when running - the logic was that most people are naturally slightly "out-toe" so making explicit effort for "in-toe" would result in "straight-toe" during running and thus maximize the feet leverage.