I have found when studying troll behavior online they will argue for vagueness strategically not only to passive aggressively frustrate the speaker but also to characterize the person to others in the conversation or telegraph to anybody they might be trolling with to respond in kind. Arguing for vagueness is often used as a preliminary positioning & bating strategy that segues into using the Moving the Goalpost fallacy with oneself as a goal, in the form of operating tacitly on the argument, “If you haven’t proven it to me, because I refuse to acknowledge what you mean, you have failed to satisfy the Burden of proof.”
You, the individual atheist, are not the scientific community. You do not know all science. Because you don’t know something doesn’t mean it isn’t known & is not a fact. Rational people are curious & want to know if they are wrong, when they are wrong. Scientific people falsify themselves & admit when they are wrong. Furthermore, DESCRIBING What an individual believes is not an Extraordinary Claim because they are not arguing for what the Scientific Community must believe. Lastly, Science doesn’t have the Authority to dictate to individuals what they must believe because that isn’t how Science works. It is not a Religion.
Moving the goalposts (or shifting the goalposts) is a metaphor, derived from association football or other games, that means to change the criterion (goal) of a process or competition while still in progress, in such a way that the new goal offers one side an intentional advantage or disadvantage.