Yeah it is. You don't just adapt to become immune to the threat. You adapt to become immune to the threat, as well as PSYCHICALLY CONTROL IT. Do you know how many threats, dangers, harms and other unpleasant things in the world exist??? Rain, fire, thunder, winds, suffocation, drowning, knives, rubberband snaps...eventually you'll be able to control them all, and when people try to strategize against you, you'll adapt to that, too, until there will be no strategy that can beat him, and he can control everything. Therefore, unless this power can be negated, as you said it can't (EVEN BY GOD POWERS, which I find odd), this power makes you not only immortal, but also omnipotent, and by virtue of omnipotence, also omniscient and omnipresent. Therefore, as Omnipotence and Omniscience, it is much too powerful and cannot (or should not) be used as an ability here (or anywhere else that is a part of THINKING society)...
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)