It seems odd, to me, that someone of Loeb's standing would put such public effort into pushing a theory about this intriguing interstellar interloper when it is

It seems odd, to me, that someone of Loeb's standing would put such public effort into pushing a theory about this intriguing interstellar interloper when it is long beyond our reach; it was noticed only when on the way out of our sensor range in the first place. Yes, an abandoned/junk lightsail might account for the behaviour noticed. But, despite the reference in the article to Sherlock Holmsian deduction, I really doubt that "all other possibilities" have been ruled out. I love the idea, though, and would be happy if it were shown to be true.