On top of that, it's a name you see on young women in their twenties and younger. The name 'Sophie' took off in the nineties, I think, and you didn't hear it much in the sixties, when this person was born. 'Grace' is a popular middle name now, but it wasn't a few decades ago.
This individual would almost certainly not have been named Sophie Grace had they been born female - Carol Jane or Deborah (Debbie) Anne would have been a much more typical name for someone born in 1964.
Obviously they can pick whatever name they like but it just adds to the overall incongruence when faced with this person.