Nobody knows his stats or powers. Would he be capable of dealing with God level threats?
its a vacant symbolic seat. If you go back to the chapter where blonde nose HA guy describes blast, it sounds like he's talking about saitama (and also that they dont know who he is, it is written in a very clever way so that it can be interpreted like that but not being the only way to read it)
eh, this is a good guess as well, though the spirits that he defeated were all pretty much very hidden in comparison to monsters in OPM
also another good possibility.
either way its understandable that if they dont know who he is, they wouldnt say such. Its nice to at least let people think that there's a secret powerful guy to help save the earth if things ever get super serious.
either way if he's someone else, he'll prolly wont appear until GOD or the end of the series