And that still would be suicide if he allowed himself to be swallowed by the black hole.

Why though? The same logic that allows him to be immune to the gravity outside of a blackhole would still apply. Curvature of spacetime doesn’t apply to him, he could just decide to fly out at any moment.

Viltrumites can not only travel fast but warp spacetime to travel FTL? And they are completely immune to gravity when flying? He had nothing to fear from falling into a black hole then. Seems like he’s assuming to effects of gravity, immune to the effects of heat and radiation. It woudn’t be suicide if he fell into a black hole, he could just fly out.