That is a good point. Below, I related epistemic stalling to intentionality, but I also agree with your response. The reason why people say things like “but you’re white” often isn’t to offer some form of argumentative justification. Rather, people say those things to function like barriers to entry: only non-whites allowed.
There are, of course, ethical issues around that kind of response, but this post is about the pragmatics of speech, not its ethics. Still, this post seems to get wrong, as you point out, the actual pragmatics of why people do what is called “epistemic stalling”.
You should address the relationship between intention and stalling. Using your example, suppose I’m the ‘stalling’ objector, but I sincerely believe whiteness matters and haven’t considered how to respond to a non-white person making the objection. I would give all the same objections you mentioned, but with sincerity. Does this count as epistemic stalling?
In your discussion here, intentionality is entirely unmentioned and absent. Intentionality’s relationship to epistemic stalling is important, because half of your post is about how to avoid epistemic stalling. If epistemic stalling implies intentionality, then people who engage in epistemic stalling won’t follow your advice—they are intentionally stalling in the first place! If epistemic stalling doesn’t imply intentionality, then sincere but poorly reasoned objectors will be (wrongly, I believe) accused of stalling. If intentionality doesn’t matter, then I think you are wrong about epistemic stalling. Stalling in non-epistemic contexts is intentional. I’m “stalling for time” when I distract a security guard while my friend escapes through the back. Since epistemic stalling is a kind of stalling, I would similarly expect epistemic stalling to imply intentionality.