Of course it's the UFC's call to make... they make the fights. If Hunt is insinuating that he's at a point in his career where training and fighting are having noticeable detrimental effects on his mental health, then how is it unreasonable for the UFC to not want to put him in that situation again and be seen as facilitating that decline further?

If we're being realistic, it's likely neither side's motives were ever 100% honest. Hunt put out the claims that he was suffering symptoms of CTE to gather support for his case against the UFC. The UFC maliciously complied by withdrawing him from his fight and depriving him of his payday. There - no more brain damage for you buddy. Neither party gives a shit about Hunt getting hit in the head again. If Hunt were truly concerned for his mental health, he would retire. If the UFC were truly concerned for his health, they would have him thoroughly assessed and if necessary, find a way to terminate his contract on terms he was happy with. But truth is this neither of them give a fuck and this is just a case of Hunt saying something he thought would gain some sympathy for him against the UFC and instead lost him an $800K payday.