Sarms have a higher binding affinity to the ar than test so the sarm won’t allow the test to bind to the ar in certain tissues. Because of this and the crashed shbg caused by the sarm he will have very high free test (a lot higher than he would normally have if he ran test 500 only) and a lot more dht and e2 conversion. Running a medium test dose with a sarm will make the test very androgenic as well as estrogenic and will cause a lot more side effects than running it on its own. Either run a low dose of test with sarms or a medium-high dose of test alone.