This sort of moderation has some precedent: "1866 the Société de Linguistique banned papers on language origins." This topic is more respectable than it used to be and now has a more objective research agenda.
In this category I'd put the following topics in that category of not really ready for a site that specializes in questions with real answers.
- Voynich manuscript
- Origins of Basque
- Attempts to tie Algonquin rock glyphs to Egyptian hieroglyps
- Some of the claims about Piraha, a language for which the reference grammar isn't widely available
I'd temper by saying, there are lots of objective questions that can be asked, such as "What examples are there of languages developing clicks without borrowing them from neighboring languages?"
"What statistical techniques are used to distinguish decorative symbols from a possible writing system?"
Can anyone think of other sexy, but probably too controversial or crackpot ideas that probably won't generate more light than heat on this site?
UPDATE: I'm was listing topics that are likely to lead to flamewars, I didn't list my particular opinions on the topics above, i.e. I'm not imply that I think the relevant parties in are crackpots.