It does in fact prevent infection you have misunderstood.
It very clearly prevents infection incredibly well, proof of that in the real world is exactly why there is excitement over this drug.
It also sounds as though you misunderstood the mechanism, it interferes in both an early and a late step in the viral process, there no theoretical reason to describe it as "not interfering with infection".
From what I read, it interferes with capsid formation. Since HIV is a retrovirus, by the time capsid formation is happening it has already integrated itself with the host cell’s DNA.
That implies that as long as the drug is present, the virus won’t be able to replicate, however as soon as the drug is no longer present the virus will start replicating. Because the cell has been infected.
Of course, the illness cannot get worse without the virus first infecting a cell, and then replicating in that cell to infect other cells in the body, and then potentially infecting other hosts; that is how a virus works, right?
Now, if replication is stopped, AND the body is able to destroy the first infected cell, then the patient is cured, but otherwise?
I guess that even if the body's immune system cannot get rid of that "patient cell zero", it is quite possible that a 6 month period is enough for the cell to die from the virus.
I do not have any medical training though, so please correct me if I am wrong.
It very clearly prevents infection incredibly well, proof of that in the real world is exactly why there is excitement over this drug.
It also sounds as though you misunderstood the mechanism, it interferes in both an early and a late step in the viral process, there no theoretical reason to describe it as "not interfering with infection".