Because, if he can't Google with enough comprehension to use umbrella (which isn't difficult) then he likely can't comprehend the steps (other than Blackra1n-which I believe no one should use) to perform a successful jailbreak.
I firmly believe there are a huge number of posters who don't have the reading comprehension and technical skills necessary to do these things and before they throw their phone in a bootloop, someone should suggest they do a reality check.
Sorry if that is a little blunt, but it is what it is. 🙂