The World Tree represented an opportunity that he couldn't miss, but reaching it alive would require strategic thinking that balanced ambition with survival.
Whilst he was technically 'immortal' in the way that once he died, he would respawn back on earth. That didn't change the fact that he didn't want to die if possible. Furthermore, based on the way that Adrian and Lola were talking, not everyone can simply take the World Tree and use its essence drop.
The person must be qualified to gain the essence drop. It was clearly one of the main reasons that Prince Adrian himself did not take the essence drop; it was because he probably couldn't.
"There's no need to rush through this without proper preparation," Noah concluded while watching the rulers continue their devastating conflict. "The World Tree has waited centuries to be found—it can wait a few more days while I develop a viable approach."