You are right, it is not currently banned. However, athletes are using it, in many sports, as a performance enhancing drug, which clearly works based on the fact that these runners used it:
Salazar
Kennedy
Ritizheimer
Rupp
Solinski
Tegenkamp
Hall
This in any court of law is evidence! And it leads to a logical conclusion!
Just because it’s not currently banned, does not mean it does not work!
Also, you can bet it will be banned in the future!
Athletes are using it to stay competitive with athletes already using it. Which explains why both Nike groups were big abusers of it.
Salazar clearly thinks it works and attributed Solinski’s sun 27 10000m directly to thyroid hormone therapy.
Would you want your kid using it in the way Salazar had his athletes using it?
If you narrowly view current rules and law as final, concrete findings, you are an idiot. Laws and rules change all the time.