I agree with the line of thought that Renarin is not bonded to a voidspren/evil. First the quoted epigraph you rely on in support of your theory - " taints a body as it breaks apart from the mind" - is slightly off, i.e. "His touch seeps into a soul as it breaks apart from the body, creating manifestations powered by the spark of death itself." I take this to mean that Moelach's touch has a chance to enter the body as a person is dying...not at will or when they are alive.
Further, although I understand Hoid doesn't know everything, in Way of Kings he speaks very highly/fondly of Renarin, which (in my opinion), he would not do if Renarin was a traitor or had evil motives.
(First time poster)