I didn't read their comment as insinuating libido is 1:1 to hyper-sexuality. I read it as: "consider if you have a libido, and depression, you may also be hyper sexually."
The situation is PersonA has determined they need an anti-depressant. So one thing is 'wrong.' It stands to reason that they may be using sex as a painkilling mechanism. After all, sex feels great. When the anti-depressant kicks in, the body may determine it doesn't have to use that painkilling method anymore, hence, the decreased libido. It doesn't mean having a libido is bad, it means that the person potentially was overdriving it.
The situation is PersonA has determined they need an anti-depressant. So one thing is 'wrong.' It stands to reason that they may be using sex as a painkilling mechanism. After all, sex feels great. When the anti-depressant kicks in, the body may determine it doesn't have to use that painkilling method anymore, hence, the decreased libido. It doesn't mean having a libido is bad, it means that the person potentially was overdriving it.