Orin looked at Lex oddly, but didn't question the human who could literally walk in dragonfire. If he said his body was weak, then it was weak. As long as he was up for Orin's crazy plan, then Orin would be up for Lex's crazy plan.
Being inside the forge during a forging was not like tolerating the heat from a volcano, nor was it like enduring the banging of a hammer. A normal forge would combine the heat, the pressure, the hammering all to create an environment that could not be endured. A normal Earth Immortal might suffer permanent, or at least long lasting injury.
