It's almost certainly pure fantasy, but you can write phd theses about almost anything nowadays! The quote came from a newspaper article, though, so in fairness we can't judge without seeing the relevant passage(s) and supporting evidence; if any. Regrettably, assertions of the kind can swiftly assume the status of received wisdom simply by virtue of being repeatedly stated; the myth that the bagpipes were banned in Scotland is a well-known example, and the internet has ensured that the process can now take place with surprising rapidity (for example, the apparently imaginary "broadside original" of Fields of Athenry).

It appears that "crack", has existed as "craic" only just long enough to have begun to appear in the most recent Irish dictionaries, and is clearly a loan-word from English, where it has a long documented history of use; though obviously many people badly want it to be Irish of long-standing. Romantic over-estimation of the age of custom and practice is something which has bedevilled folklore studies over the years; consider how many people insist that the bodhran is some sort of ancient war-drum, or that Henry VIII wrote Greensleeves.

For myself, I find the insistence on spelling "crack" as "craic" (and "session" as "sesiun", come to that; perhaps more so) rather silly and pretentious when writing in English, though both -recent loan-words though they are- are perfectly properly spelled in that way when writing in Gaelic. Probably the majority of those who use these modern transliterations have little or no Gaelic, however, and are simply following fashion or what they have been told is "correct". I wonder how many, when writing of buying stamps, say that they have been to the "Post Oifis"?