High natural testosterone is likely for former steroid users if they wait long enough to recover. Most declare "permanent shutdown" after 6 months to a year, but the truth is that LH and FSH rise dramatically in response to low testosterone. If you look at the LH and FSH of men over 75, whether former steroid users or not, they usually have very high LH and FSH. They have low testosterone from the actual aging of the leydig cells in the testes, which no longer respond to LH and FSH. If a young man had the LH and FSH of an 75 year old man, he'd have very high test.
The rise in FSH and LH with increasing age is consistent with the decline in testosterone, assuming normal operation of the feedback pathway by which low testosterone level signals the hypothalamic-pituitary axis to release FSH and LH(
https://pmc.ncbi.nlm.nih.gov/articles/PMC3073592/)
That being said, whether 900 is "good" or not, it's fantastic for healthy aging but horrible for competitive bodybuilding because it's too high for any doctor to prescribe testosterone or anabolics, but too low for noticeable muscle gain above what you would have at say 700.