If his HPTA is screwed, its screwed, a test cycle won't make it much more worse.
and maybe some hcg and low dose nolva during cycle may help.
If he's low in test, a test cycle could heal him temporary. then start a proper PCT and maybe he'll be fine.

I can remember I never had a great libido in my life, after my first h-drol cycle, my libido was completely down.
I could get erecctions, but girs had to force me to have sex.
then after PCT I waited a month or so, and did a proper test tren cycle.
My libido was extremely high, and guess what, I did a proper PCT again, and after that PCT, I was able to have sex ED for 3 months or so, since I started another cycle.
now I NEED sex ED, because I get crazy if I don't, and I guess after PCT, it won't be very different. maybe not that hardcore, but I think psycology plays a very big role.