My personal conspiracy theory is that "Isis" is a result of the US "convincing" media organizations to use that name for the Islamic State after realising that intercepting communications using the term "is" was an impossible task. Even further, they then tried to impose "Daesh" but it didn't catch up.
Didn't they get death threats and insults on Facebook? Not only from people that would do that kind of stuff online, but also the kind of person that thinks that a terrorist organization has an official Facebook page.
They had to rename their page to "ISIS the band" or something like that.
[1] https://en.wikipedia.org/wiki/Softcard