I don't think being an expert in a field prohibits you from getting hired by valve. Her project comes across to me as R&D where a small team of experts are working with something trying to find an application, while she seems to come across as wanted to scale up and produce something functional now.

From my POV it almost certianly sounded like she actually needed software folks, as opposed to additional hardware, because the nudges from valve were that her project had to actually display some interesting game play before anyone would be interested.