To turn this question on its head, I'd like to propose a different question that the AIDS deniers haven't answered.
If HIV were not the cause of AIDS, why would anti-retroviral therapy be so successful in preventing the disease? Each of the meds in the cocktails that stave off AIDS limit the ability of the virus - the HIV virus - to reproduce.
It can be argued that AZT is effective against more viruses than HIV alone. Reverse Transcriptase (necessary for viral replication) is an enzyme necessary to the replication of many viruses. However, the AIDS denialists claim:
...because the drugs are anti-viral and anti-bacterial in nature, they give a false impression of being effective for treating HIV infection. What appears a miraculous recovery in many patients is, in fact, the drugs’ effects upon the opportunistic infectious agents the person may harbor at the time, other than HIV. (from your source)
AZT is not an antibactial. Antibiotics (as well as things not to be taken internally, e.g. bleach) are antibacterials. Antibiotics treat Pneumocystis jiroveci (formerly known as Pneumocystis carinii) and other microbial infections; they are useless against the common cold and other viruses.
Pneumocystis first came to attention as a cause of interstitial pneumonia in severely malnourished and premature infants during World War II in Central and Eastern Europe. Today, it is more common in immunosuppressed patients:
Clinically significant Pneumocystis pneumonia is virtually never observed in immunocompetent adults. Indeed, documentation of Pneumocystis jirovecii
in a patient without known underlying disease should prompt a careful search for occult immune suppression... trimethoprim–sulfamethoxazole [the antibiotic Bactrim] remains the most effective regimen for treating severe Pneumocystis pneumonia... Patients with previous Pneumocystis pneumonia should receive lifelong secondary prophylaxis, unless reconstitution of the immune system occurs. ...Ledergerber and colleagues analyzed episodes of recurrent Pneumocystis pneumonia in 325 HIV-infected patients after they had peripheral blood CD4 cell count greater than 200 cells/ml and found no cases of recurrent Pneumocystis during a follow-up period totaling 374 person-years. Prophylaxis should be reintroduced if the CD4+ count falls below 200 cells/ml.
An antibiotic can treat P. pneumonia in HIV-infected patients, but cannot restore immunocompetency; only anti-retrovirals can.
The standard treatment [of HIV] consists of a combination of at least three drugs (often called “highly active antiretroviral therapy” or HAART) that suppress HIV replication. Three drugs are used in order to reduce the likelihood of the virus developing resistance.
On the near-miraculous effect of combined antiretroviral in the treatment of HIV, your paper observes:
Because these drugs also attack non-infected cells, they can destroy the immune systems’ healthy T-cells, and even cause a collapse identical to AIDS.
But they offer no evidence of such a claim. No drug is without potential side effects. Some antibiotics can cause aplastic anemia, a condition certain to result in an immunocompromised status. However combined antiretrovirals save lives, they do not cause AIDS.
The paper is full of similar holes.
Deniers gain footholds by building straw men and knocking them down, not by advancing credible science.
Untreated, HIV causes AIDS. Anti-retrovirals prevent it's development.
An Official American Thoracic Society Statement: Treatment of Fungal Infections in Adult Pulmonary and Critical Care Patients (2010)
World Health Organization
White swans, black ravens, and lame ducks: necessary and sufficient causes in epidemiology
Inventing the AIDS virus