The problem I have with the concept that Gaelic identity is a chosen and/or learned cultural identity, rather than an identity limited to those who are born to it as one's ancestry, is the same problem I have with the concept that Native American identity can be a chosen and/or learned cultural identity.
What then happens to the people whose ancestry it actually is? If you go to any of the areas of Ireland or Scotland where native Gaelic speakers (most of whom are now bilingual) live and work, there is no different mode of dress, the foods eaten are the same as those of the rest of the country, with local exceptions, the religions are the same, etc. So the only significant differences nowadays between a Gaelic speaker and an English speaker is the language. So if someone with no familial ties to Gaelic ancestry decides to walk around playing Druid, what does that make someone with familial ties by birth or by marriage to Gaelic ancestry, whether living in the Gaeltacht or New York City? Chopped liver?