I think it is evidence that thinking about it carefully wouldn't advance their current concerns, so they don't bother or use the thinking/talking for other purposes. Here are some possibilities that come to mind:

• they might not care about the outcomes that you think are decision-relevant and associated with your claim

• they may care about the outcomes, but your claim may not actually be decision-relevant if you were to find out the truth about the claim

• it may not be a claim which, if thought about carefully, would contribute enough additional evidence to change your probability in the claim enough to change decisions

• it may be that you haven't framed your arguments in a way that suggests to people that there is a promising enough path to getting info that would become decision-relevant

• it may be because of a signalling hypothesis that you would come up with; if you're talking about the distant future, maybe people mostly talk about such stuff as part of a system of behavior that signals support for certain perspectives. If this is happening more in this kind of case, it may be in part because of the other considerations.