I don't think the issue has been as definitively settled as you have been persuaded to think. Let's take a look at the claim "if there is a 'platonic mathematic

I don't think the issue has been as definitively settled as you have been persuaded to think. Let's take a look at the claim "if there is a 'platonic mathematics', we cannot have any direct experience of it" (I realize this is probably a paraphrase of a fuller argument, but it is what I have to work with here.) Firstly, note the word "direct" here. If it has any relevance, then the authors have assumed the burden of explaining either that there are only direct experiences, or why indirect experiences don't count. Secondly, what are the premises here? If this is supposed to be axiomatic, then there is literally no reason to either accept or reject it, and claims that the issue has been settled are just statements of belief; otherwise, the argument needs to have premises that are not begging the question in some way. As it stands, this claim is not an argument; it is more of an intuition pump. Metaphysical discussions tend to (always?) end up as being about the meaning of words like 'real' and 'true'. Whether such discussions can really tell us anything about what must be true is arguably the most meta question in metaphysics.