Nothing suprising about that study.
Keep in mind that with HIV positive individuals, body weight is probably more reduced than normal,
meaning that AAS even without training will have a much more profound effect than in an athlete with developed muscles.
In essence you can say that the bigger (more muscular) you are, the less you will gain from x amount of steroid or training.
This should come as no suprise to anybody here, we all know that the closer you are to your Genetic limit, the more you need to do right.
Or on other side; a beginner will gain by doing almost anything.
On a side note, check out the strenght gains in the study.
In some excersises there was almost zero increase without training,
and in all excersises strenght increase with AAS & training was greater than you would expect with the increased muscle size from AAS alone.