This isn't about the Lancet specifically. It's about someone on the internet challenging the overwhelming medical consensus without providing a shred of evidence to support their claims. I can assure you that 'people saying things on the internet' have a far worse record on medical matters than the Lancet, or the medical consensus more generally.
You could try asking a virologist if they think it's possible for the HIV-1 provirus to ever be in a state where it could theoretically be infectious given the right DNA fragmentation.
i've no opinion on the topic at hand, but I would urge you to find a plethora of signals to form your opinions.
The Lancet has been responsible for quite a few negative 'public health' trends.
The Lancet is responsible, at least partially, for the whole 'vaccines == autism' thing of Andrew Wakefield's; and even ignoring that they have a history of poor review and retraction of work that ends up either being entirely wrong, or guilty of experimental misconduct.
In 1992 they published stuff that suggested a causal link between HIV infection and the oral polio vaccines.
In 1998 they published a (big tobacco funded) peper indicating that second hand smoke doesn't have as much risk as earlier thought.
In 2000 they published a study that claimed that St Johns Wort was as effective an anti-depressant as conventional SSRIs and TCAs.
Just because something has become 'prestigious' doesn't mean it should be trusted wholeheartedly.