There is so "slander" as my statements are true and all backed up by factual references. BTW, if you write a post accusing someone of slander when there is no slander, that is libel. Unless you want to continue doing that, you should stop. And again, this isn't a business, it is public criticism and debate about open source projects.
I'm not sure but I suspect anonymous screennames on internet forums can be defamed with impunity.