comes from what was stated in Sanctuary For All and then later in Haunted. Sanctuary For All used footage from webisodes 1-3 but they changed the "family reunion" from webisode 4. In the Webisodes, John's illness was caused from the teleporting and each time he teleported it caused his madness to increase. Also in the webisodes John was able to teleport through time and not just space so there was no need to give John long life as he just moved through time. Then in Haunted....Amara
just in case you peaked I'm spoiling this again DON'T CLICK THIS ONE!!!!
I hope I explained it and it made sense (kinda late here)if not just ask and I'll try again when I'm not tired