Yup, I'm in complete agreeance.
I would let her know that while I respect her voicing her "concerns", I cannot make any promises as to what/how many/which ages of children I am taking in. I reassure her that I would not at any point take in any kids that I didn't know for sure I would be able to handle to the best of my professional abilities.
I don't know that I would turn them away at this point, but I would certainly be on the lookout for any other "signs" that this relationship isn't going to work.