He couldn't be blamed, his body was still feeling the desire to devour more energy and thus choosing to jump into the magma, something that could be seen as bold. He didn't just do it, because he had the desire to absorb more energy, rather his next path of cultivation would become very difficult. He needed immense amounts of energy. This was something he thought the depths of this boiling magma could solve.
Under the magma, it was Indeed just as he thought, but the place was also divided into layers, and the lower he went, the hotter it become. The energy his body was absorbing was also increasing at an alarming rate but I couldn't cause much waves in this place. Just streams of white mist could be seen moving towards his body, after that they vanished. It seemed that his body was not even affected by the fire poison in the slightest. As for his soul, he was using the Black and White Flower technique to strengthen it.