can an unemployed person publish an article
Anyone can publish an article if it is accepted by the editors. There are no restrictions in any reasonable circumstances. Of course, there are places where publishing anti-governmental articles is dangerous but that is a different question. 

Editors want to see some "affiliation" for authors, but that is mostly for identification purposes. Others have been named Schopenhauer, of course. 

Science and academia generally are driven for the most part by ideas, not by prestige, though the latter gets in the way on occasion. But the ideas of luminaries are questioned as well as those of unknowns.