Actually, it was Mokuba who saved him. Mokuba cuts off the power line because Kaiba's brain activity is going into dangerous levels, thus forcing Kaiba and Sera to be forced to log out.
Sera on the other hand, keeps her promise and is completely ready to bring Kaiba into Atem. She has a neutral stance however, as she does warn Kaiba about dying, but Kaiba just ignored it.
Anoymous
Seto Kaiba