The deleted Saint Thomas memoirs were just one more perspective on the biography of Christ. If I had been alive at the time, my own interpretations would have been different again. The writers' idiosynchrasies cannot be taken as right or wrong. For the record, Thomas' gospel was deleted becasue some leader fancied that he was implying that homosexuality should not be prohibited.
I think it is best not to worry too much about the technicalities and decide whether Christ's philosophies such as that of "turning the other cheek" are useful. Many would say they are good to live by, some would say that the old testament motto of "an eye for an eye" is more appropriate. Saint Paul's teachings are merely his own, very stylised thoughts on the gospels, which are no more valid than anyone elses interpretations (Saint Paul makes alot of odd and contradictorary assertions which are entirely his own)