On the Topic of Antigone's Textual History...

It is honestly impressive how long Antigone endured as writing on papyrus. I'm not sure how durable papyrus is, but the fact that legible scraps of papyrus were found in Egypt is mind-boggling. I'd have to imagine that the script was brought by land rather than washed ashore, though the positioning on the coast of Egypt doesn't indicate a clear answer; that being said, it wouldn't make sense to me for the papyrus to still be legible after spending enough time in water to be washed onto the shores of Egypt. 

Anyway, it is just as impressive how the story was adapted through over a millennia's time. Certainly, the specific diction may have been altered with the passage of time, but the overall narrative remains unchanged.

With regards to the change of the speaker at line 572, it is merely the translators/adapters trying to reason who, with knowledge of their characters, would be more logically suited to speak the line. It is not difficult to see why it would be assumed that Antigone would be more suited to a line addressing Haemon, her unwed husband, with adoration. Could someone, the earliest confirmed being the Aldine, have knowingly changed the speaker of line 572 to Antigone? Perhaps, but again, this would have had no impact on the greater narrative, and would have made more sense to the isolated story of Antigone. The most damage done would be to the reputation of the editor, and the sin, if you could call it that, of knowingly changing the text that one is assigned to faithfully adapt.