This stupid rumor has been going on for over a decade. I have no idea where it originated but like many Silent Hill rumors that become oft repeated myths, it is not a fact and has been disproved. Still to this day people keep repeating it. Most people don’t even know who Samael is in real world mythology that SH draws from, however, an “incubus” is not one of them in any format.
The rumor is up there with “Valtiel is the yellow god because it’s yellow and Pyramid Head is red so therefore it’s the red god.”! It’s sloppy and lazy. It ignores primary sourced material and things the creator’s actually said. Now the myth is so big in the fandom and abroad, that even things such as wikias cite it as “fact” without consulting supplementary material or even in game material. Just because something is often mistaken or oft repeated by people does not make it objectively true. (Ad populum fallacy)
It does not help that the more something is said, the more true it appears. Science has confirmed this as an actual phenomena and SH fans fall into this trap time and time again without actually reading the vast amount of Silent Hill supplementary material or in game memos to confirm it’s accuracy!