Maybe? I assume the pin is stainless steel but am not positive.Can you use ACV with the nipple system? (metal parts)
I do know that there are many 'grades' of stn stl, and some are much more apt to corrode than others,
and those grades are rarely specified outside of pharmaceutical and sometimes food processing equipment fields.
Maybe sacrifice(possibly) one and put it in full strength ACV and see what happens after a week or so?
If I really wanted to know, that's what I'd do.