Yes, they’re talking about idiopathic CD4 lymphocytopenia (ICL) - which just means “a deficiency of CD4+ T-cells for no apparent reason”, whereas in AIDS you have a deficiency of CD4+ cells caused by HIV. The loss of CD4+ cells is an unusual immune system defect that makes you vulnerable to certain rare infections, which is why AIDS was so quickly recognized as a new disease - but there’s no reason that a particular system in the body can only be damaged by one cause, so the existence of (still extremely rare) cases of ICL isn’t necessarily relevant to HIV/AIDS, any more than the existence of “blindness without glaucoma” means there’s no such thing as glaucoma. ICL doesn’t really behave like AIDS, either: the patients don’t usually suffer progressive loss of T-cells, they just stay low, and there’s been no evidence of contagion as far as I know. I don’t think the study of ICL has advanced much in the last 10 years, mostly because it is awfully rare; the consensus seems to be that some cases are due to genetic problems and others are still a total mystery.
It used to be somewhat mysterious how HIV caused CD4 cells to die (the “AIDS dissident” Peter Duesberg made much of this, claiming that because it didn’t behave like other pathogenic viruses he’d studied, it couldn’t possibly be harmful) - but immunology and virology have come a long way in the last 20 years, and there’s now a pretty strong consensus on how the virus works. Unfortunately, that doesn’t translate directly into being able to stop it.
It’s admittedly confusing that the name of AIDS seems to just describe a general symptom (immune deficiency), but things often get named that way in medicine based on whatever the earliest investigators noticed first - for instance, diabetes was named after the symptom of excessive urination. Many clinicians now use “HIV disease” to refer to the infection in all of its stages, since the definition of AIDS only applies to a somewhat advanced stage.