I think he's the same guy that said Oumuamua maybe was an alien ship because of its strange speed change. I think he said rational things, and his point is not "alien visited us", but "we can not reject this possibility". If an alien ship crashed there and those little balls didn't disintegrate in our atmosphere, than there's a bigger scrap out there. We must find it, that's all for now. I think the "spherules" won't say us nothing more.