There is absolutely zero chance a cruise missile would be fired without closing the airspace to civilian aircraft.
The pilot was at 37,000 feet and said the object was above them. Commercial planes top out at about 42k feet and would have shown up on ADS-B. A U-2 flying at 60k would look like a long cylindrical object about the size of a cruise missile (in the same way a 747 looks small from the ground), and not show up on instrurments. Oh and they regularly fly out of Nevada to swoop down over New Mexico/Texas on their way to Mexico and Central America.
The pilot was at 37,000 feet and said the object was above them. Commercial planes top out at about 42k feet and would have shown up on ADS-B. A U-2 flying at 60k would look like a long cylindrical object about the size of a cruise missile (in the same way a 747 looks small from the ground), and not show up on instrurments. Oh and they regularly fly out of Nevada to swoop down over New Mexico/Texas on their way to Mexico and Central America.