Thank you for your answer Marilyn (Mickey330). That is now clear to me. For my surprise whenever people are mentioning these upgrades to their devices it is not clear that there is no way to update to a given firmware if you don't have the SHSH blobs for it. I spoke to my friend and he is waiting on the untethered jailbreak for 6.01 then.
Too bad that his phone is not unlocked, he only needs the jailbreak because he must use the ultrasn0w to unlock his device to other SIM card companies.
Again thanks for your cooperation.