I can 100% confirm that as of the current time you don't need to be below 70km to fulfill "in flight" contracts. I just put a guy into orbit for the same reason you did and then wasn't able to fulfill a contract when I tried to pass over a spot. That's what led me to this thread. I wasn't sure if I had missed it or if you weren't allowed to do it from orbit. I just did another one from 73,xxx meters, but my periapsis was 68,xxx, so maybe you can't do it from "full" orbit, but you can definitely do it from some kind of orbit. I'm pretty sure 69km periapses are not considered orbits for some other contracts.
I cannot 100% confirm full orbits won't work; I can 100% confirm that "suborbital" orbits will work no matter the actual altitude.
