There’s a nuanced post over at Assistant Village Idiot about how claims of language victimhood don’t make plausible etymological explanations more probable.
Linguistics is about proof; etymology is about probability. That’s an unfair simplification, but it will do for now. Cassidy and others who wish to defend Irish honor in the field of contribution to English get quite caught up in the oppression aspect, and recognizing Gaelic roots of terms begins to take on an aspect of “We have to do this to right ancient wrongs. Damn the English and their dictionaries.” The more you read, the more you descend into the rhetoric and evidence of conspiracy theorists. Baseball writers used “jazz” early, baseball players were largely Irish, they went to Hot Springs Arkansas where there was an Irish population, they used the hot springs and came back to California talking about “jazz” as heat and energy—what more do you need for proof you English bastards?