True. However, why does there exist a great insistence about the timing of the writing of the Thomas "gospel" by those who wish to assert its authority and inspiration as equal to the four canonical gospels? Doesn't that matter in regards to its claimed authenticity? The title in your post says it all, "These are the secret words which the Living Jesus spoke and Didymos Judas Thomas wrote". Really?
If that claim is proven untrue, then what of the rest of it? Also, the four Gospels have 4 key elements in common whereas these are either contradicted, diminished or ignored in the other non-canonical "gospels"...
(1) the apostolic preaching about Jesus, from the beginning, involved four key elements; (2) all four of the canonical gospels have these four elements in common; and (3) the extracanonical gospels do not, and in most cases do not clearly have any of them. These four key elements, identified by Paul in the mid fifties and clearly representing an even earlier tradition, are summarised in 1 Corinthians 15:3-4: (i) the identity of Jesus as the Christ, anointed by the creator God of Israel, (ii) his fulfilment of the Jewish Scriptures, (iii) his effective atoning death on behalf of others, and (iv) his bodily resurrection from death.
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If there exists contradictions in fundamental theology between the Four Gospels and the non-canonical "gospels", what do you hold as true?