the beginning and the end (spoilers)

There's a theory that, to quote the FAQ, "Prot did indeed leave Earth to return to K-PAX, taking Bess with him. Porter was just a human host that prot used while on Earth". In this case, it's not completely surprising that Prot would leave the Porter host body behind when going back to K-PAX by some sort of incorporeal light transport. But Prot seems to arrive on Earth, at the station, in the body of Porter. If he didn't travel to K-PAX in that body. surely he didn't travel from K-PAX in that body either. So where did Porter's body come from? It's stretching it for Prot to instantly slip into a waiting Porter body (which without him seemed to require a wheelchair) in the middle of the station, and we - like the crippled beggar - just suddenly see Prot appear in the form of Porter. Should we think that Prot didn't make use of Porter's body, but rather replicated Porter's body, with extraterrestrial expertise? It would have been less problematical if for example instead of the station scene we had seen Porter comatose in a hospital bed, and then miraculously conscious and displaying an alien intelligence.