There is no reason not to have an article on Immanuel, or innumerable other pseudoscientific phenomena / fads / people.
My opinion on fringe materials is to be inclusive in terms of having articles or descriptions, but make the descriptions from a mainstream perspective. Velikovsky was not in the end a scientist; nor was Hoagland, or others of note recently. We have articles for them, and their most important theories, as we should. The articles need not confuse the issue by telling readers to lend the fringe theory as much credibility as one does normal mainstream science.
Wikipedia specifically tells us to describe things from a neutral point of view which Jimmy Wales says is "absolute and non-negotiable".
That's not to say that we exclude the scientific point of view, or even the mainstream scientific point of view. But we do tell people there is a mainstream point of view, and point people to the appropriate article, and/or, provide criticisms where they exist.
When we describe the Republican point of view, we don't automatically counter-point from the Democratic point of view.
I would expect a scientific encyclopedia to assume a mainstream scientific point of view.
Regards,
Ian Tresman www.plasma-universe.com