Let's follow the logic of Clement to help identify the context of Clement' being "judged worthy for the hearing of the words of blessed and worthy men" (ὧν κατηξιώθην ἐπακοῦσαι, λόγων τε καὶ ἀνδρῶν μακαρίων καὶ τῷ ὄντι ἀξιολόγων" (1.1.11.2). The list that follows then does not suppose a face to face encounter with the men. There is no reference as far as I can determine of him actually 'seeing' the Ionian, the one from Coele-Syria etc. The determining experience is coming into acquaintance with
hearing them. Notice also that Clement himself is 'judged worthy' κατηξιώθην of hearing the "worthy" (ἀξιολόγων) men to the extent that he becomes like them. This is the key to making sense of the passage. Clement hears the Ionian, then the Coele Syrian, then the Egyptian (both in Magna Graecia), and then he hears three more in the East - the Assyrian, the Palestinian and finally the hidden Egyptian. But the underlying experience is always the same - he has been judged worthy in each case to be brought into acquaintance with their hearing. No mention whatsoever of 'seeing' anyone.
I think that Clement is hinting in a way that he wrote a gospel. Of course he is doesn't say that nor does he give the name of any of his sources - let alone his final 'hidden' Egyptian source. But the context here at the beginning of the Stromata is a context for the work that will follow. The work is aimed to prevent 'forgetfulness.' What sort of 'forgetting' is he talking about? It would seem that each gospel he has come into acquaintance with has only been read to him. You don't walk away with a copy of the gospel. To this end this is exactly the scenario described in his Letter to Theodore regarding the 'secret' text guarded by the Church in Alexandria:
Thus, in sum, he (Mark) prepared matters, neither grudgingly nor incautiously, in my opinion, and, dying, he left his composition to the church in Alexandria, where it even yet is most carefully guarded, being read only to those who are being initiated into the great mysteries.
In other words, if you happen to be in Alexandria and are accounted worthy of being brought into acquaintance with the text the hidden Egyptian gospel will be read to you. But after you leave you have nothing to take with you.
“Finally, from so little sleeping and so much reading, his brain dried up and he went completely out of his mind.”
― Miguel de Cervantes Saavedra, Don Quixote