For me, the link went to an article behind a paywall, so I will rely on your account. All the mirror can do is reflect an image of the sun. But, if we assume (extremely generously) that the mirror is only 100 km from any ground site, it will have an angular diameter about 1/52 of that of the Sun. Which means it will reflect only 1/2690th of the sun's area (about 0.037 percent). All that trouble to produce only a visual annoyance? (The f-number for such a system would be no better than f/5,555, so I don't see it as being much of a "concentrator".)

It's not even a new idea. Krafft Ehrike proposed "solettas", circa 1970, mirrors of MUCH greater size, stemming from Hermann Oberth's ideas of the 1920s. (Hard to find information on solettas. Here is a link to an abstract of one of Ehricke's papers on the subject: https://www.sciencedirect.com/science/article/abs/pii/0094576579900031). I was privileged to meet and chat with Ehricke several times in the 1970s. He was quite a rousing character. As a boy, I built plastic models of the things he was dreaming up when he was at Convair.