Can I suggest you read the thread? Then maybe you might realise that your posts have been like a rinse and repeat cycle.
As others have pointed out, this thread really is stuck in a cycle of repetitive points being raised and answered and women being told that they are mean and have assumed the worst.
To answer your question, no. He didn’t actually have that discussion. But think about this. What do you believe the resulting discussion would have been if she, the teenager, said she would like help?
What ‘help’ would that male member of staff be able to give her that didn’t involve a discussion about style, size and usage? What next step after ‘can I help’ would not involve discussion of the product in that bra dept?
Or do you think he was asking a girl is she needed help, while she was not walking around looking for help, to then say ‘I will get someone else’? If that was the case, why didn’t he alert a female staff member from the start?
Yes, he could be poorly trained. But it is probably more likely that he either understood his presence would be unwanted as it was a teenaged girl in a bra section he approached or had been so assured by people who have fully supported his belief that he is female that he acted as if he was a female member of staff.
As you agree, it was in appropriate in any case.
As the mum has been clear on twitter about her aim for her complaint, she wants M&S policy to centre appropriate safeguarding.