The only way you get into the difficulty at all, is by rejecting any explanation other than the one saying it was a missile.
But the fact remains that there is a much simpler explanation -- a mundane one, alas -- for which there is supporting data, in terms of timing, location, and visual signature.
It was a contrail, FRiend. You can go outside some afternoon and watch any number of similar "missile launches" pass overhead as airliners and cargo jets wing their way to their destinations at high altitude.
***shrugs****
Well that contrail has fooled a lot of ‘experts.’