Tbh it has been open since end of March I have found - there is usually a tensa barrier across the entrance but you need to speak to the security agent hovering nearby. I did use it a few times by showing a bp and saying I was in business - but I agree it wouldn’t surprise me if BA were not paying.
Tbh I haven’t bothered with it for the last week or so since it has been quiet when I arrive around 0515-0600. I haven’t encountered queues of more than a dozen in normal track, and often it’s been only 2-3 people in front.
I agree though with your other comments. Also considering there is little space after the scanner and loads of people waiting for secondaries, the whole place is a nightmare for social distancing.