Einstein didn't have an academic position, but he was still operating from within the professional world of physics in 1905, his
annus mirabilis. He completed his PhD early in that year, and he'd already published several papers by then; he had enough of a reputation that he started writing reviews for
Annalen der Physik the same year as well. Also, his revolutionary papers were more a matter of reinterpretation of existing physics, rather than a wholesale replacement of existing theories. Special Relativity, in particular, has clear antecedents in the work of Lorentz and Poincare. In contrast, the paper in question here would completely gut the prevailing theories in both cosmology and particle physics.
Edited by sfs, : No reason given.