speed of light

if any observer moving slower than the speed of light observes the speed of light to be a constant, does that imply that any observer moving at the speed of light observes anything moving slower than the speed of light to be moving at the speed of light, relative to itself?

i.e.:  if light could measure, would it observe a car and a comet to be moving at the same speed?

this question never had anything to do with sending a human body at c, so visible spectrum doesn's matter.  i think you're all misinterpretting his use of 'observer'.

looks like the question is just, if light moves at c relative to us, do we move at c relative to light.  like, is the velocity the same both ways.

but i don't even know if the velocity is the same both ways between any two things moving at different speeds, in GR
i.e. if a spaceship left earth, would the velocity earth measured it to be traveling be equal in magnitude to the velocity the ship measured earth to be traveling