HGH is not allowed in MLB you maroon. Whether legal or not, MLB does not allow its use.
HGH and Steroids were allowed in MLB until a couple of years ago. You have to separate the Federal legal aspect from the MLB legal aspect.
Use of HGH without a prescription is illegal. There are very few valid reasons for an adult to have a script for HGH. It is not the fountain of youth as described by the MSM or dumb jocks - otherwise you or your close friends would likely be using it and it would be as common as Starbucks.