@Theunamedcat
No, the op has never said it was a joint decision. She mentioned the consultant advised it, but has not said that the baby has any extra vulnerability (babies are not vulnerable by virtue of being babies, and the guidance allows contact to continue as normal), or the context.
It may be that the baby had respiratory issues, and is under consultant care, and that's how it came up.
It may have been an offhand chat with the doctor signing off the baby at birth, with asking 'do you think it's a good idea for baby to see relatives that have travelled by train' without specifying that it's the babies own father.
The OP has not elaborated, and if there were a specific reason why fade to fade would be dangerous for THIS baby, then I'm sure she would have mentioned it.
That she has been asked more than once and has still not said whether the baby is ECV, for example, or that it is agreed, makes me think there isn't a real reason, and it's the OPs anxiety over Covid, or her not wanting direct contact.
Up and down the country, seperated parents are seeing their small babies. Unless there is a medical reason why not, I don't see what is so different here.