In a later storyline, T’Challa and Black Bolt were willing to leave Namor to die after he’d formed a cabal of villains to properly protect Earth, despite the fact that Namor had already turned against this cabal after realizing the other members had gone too far.
As mentioned earlier, there have been times in the comics when Namor the Submariner has been presented as a super villain.
Namor and T’Challa had a relatively good standing with one another in the years beforehand, but obviously once the former wiped out the latter’s home, that scarred their dynamic.
One example of this is when he destroyed Wakanda during the Avengers vs. X-Men storyline.