I do think their muscle would still be significantly reduced by the hormones, but the older someone is the more their body is “set in place.” This means any changes will take longer to occur and they may not happen to the degree that they would have if they started younger. So someone starting mid 20s - 30s likely won’t have skeletal changes, since that part of their body has already finished growing. (Someone starting as a young teen definitely will have skeletal changes though.)