A time reversed photon is still a photon, and as such photons in Feynman diagrams aren't given a direction. They're equally valid to view traveling forward or b

A time reversed photon is still a photon, and as such photons in Feynman diagrams aren't given a direction. They're equally valid to view traveling forward or backward in time. This is as opposed to an electron, which is given a direction, because reversing it in time produces an anti-electron.