Let's not overlook the decades of prior data! The field is littered with names like VRC01, Camelid and so many other players. I know, I know, antibodies all versus antigen in this case. But keep reading ...
HIV is a master at developing resistant forms of itself. What if it changes the epitope and evades the vaccine induced antibody(ies), again!?! (Edit: Don't forget the long-term viral reservoirs that survive against the best antiretrovirals known to us!)
This is something I care about personally: What is their strategy against resistance? (Or, like everyone else before them, they will build that bridge when the water is above their nose!?! Not being snarky, just very concerned.)
And might I also ask: Any concerns about accidentally inducing an autoimmune disorder with that antigen/epitope? Why/why not?
Added: I'd love to see these guys succeed and really want to see a rationale and approach that goes beyond what has been tried and not worked so far. Also, kudos for the open-science approach!