An excellent question, Glenn. The defining marker between contemplative scenes and suspense scenes is where the source of conflict is coming from: is it internal or external? I’ve defined contemplative scenes as more reflective as the viewpoint character comes to terms with something. This means the conflict is internal. The viewpoint character is thinking about their situation, perhaps trying to decide what to do, wondering if they did the right thing, or wondering if whatever’s going on is their fault. Contemplative scenes are often an internal debate. Suspense scenes however tend to have an external source of conflict. The viewpoint character is actively engaging with someone or something, but the outcome is uncertain, the pacing is slower (than an action scene), and there is a heavier reliance on tension that keeps the reader hooked.

While hybrid scenes do exist, I would argue that one of the defined scene types will always stand out as more prominent. The Heinlein scene you are describing sounds like it is a contemplative scene because the conflict of the scene is internal. Yes, it has suspenseful elements, but those elements are building suspense for the broader story not this specific scene.