The Gospel of the Hebrews: Did I just say something dumb?

In his Dialogi contra Pelagionos 3.2 Jerome quotes a gospel which he calls the Gospel according to the Hebrews. Here is A. F. J. Klijn’s translation:

In the Gospel according to the Hebrews which was written in the Chaldaic and Syriac language but with Hebrew letters, and is used up to the present day by the Nazoraeans, I mean the Gospel according to the Apostles, or, as many maintain, the Gospel according to Matthew, which is also available in the Library of Caesarea, the story runs: “Behold, the mother of the Lord and his brothers were saying to him: John the Baptist is baptizing for the remission of sins. Let us go and be baptized by him. But he said to them: ‘How have I sinned, that I should go and be baptized by him? Unless perhaps something which I said in ignorance.’”
Jewish-Christian Gospel Tradition (Leiden: Brill, 1992), 103.

And the Latin:

In evangelio iuxta Hebraeos, quod Chaldaico quidem Syroque sermone sed Hebraicis litteris scriptum est, quod utuntur usque hodie Nazareni, secundum apostolos, sive ut plerique autumant iuxta Matthaeum, quod et in Caesariensi habetur bibliotheca, narrat historia: Ecce, mater domini et fratres eius dicebant ei: Joannes baptista baptizat in remissionem peccatorum; eamus et baptizemur ab eo. dixit autem eis: Quid peccavi, ut vadam et baptizer ab eo? nisi forte hoc ipsum quod dixi ignorantia est.

The thing that interests me is Klijn’s translation of the last sentence. Klijn interprets the words nisi forte hoc ipsum quod dixi ignorantia est as an admission that Jesus may have sinned in ignorance, translating it “Unless perhaps something which I said in ignorance.” Assuming that hoc ipsum quod dixi refers to hypothetical past sins of ignorance, Klijn’s translates it as “something which I said.” This assumption seems questionable to me for a number of reasons: 1) hoc (this) is used to describe a thing close to the speaker, as opposed to illud (that). 2) hoc is not indefinite. One would expect aliquid or quoddam or the like if “something” were the correct translation. 3) ipsum intensifies the definiteness of hoc. 4) The use of est rather than erat also points to the immediate context rather than past sin, unless it’s a historical present. 5) hoc is restricted by quod dixi, so according to this interpretation hoc would refer only to past sins of speech.

For these reasons it seems far more likely to me that hoc ipsum quod dixi refers to Jesus’ immediately preceding words. Thus, the sentence may be paraphrased “Unless that which I just said is incorrect.”

Recently I stumbled on J. K. Elliot’s translation in The Apocryphal New Testament: “But he said, ‘What have I committed, that I should be baptized of him, unless it be that in saying this I am in ignorance?’” Sounds good to me.

Here’s why this question is interesting to me: according to my favored translation, Jesus dithers almost comically, objecting to the thought of baptism but then shrugging his shoulders and admitting that he might be speaking nonsense. This depiction would be at loggerheads with that other Gospel of Matthew, where Jesus overcomes John the Baptist’s objection with the words, “Let it be so now, for it is fitting for us in this way to fulfill all righteousness” (3:15).

Would anyone like to defend Klijn’s translation? Am I missing something?