like I get what he’s saying, he’s saying “Don’t say /v/, say /β/ instead”

That’s shurely better than the Saxoid thing of always saying /v/ and never /β/, but even de Bhaldraithe in The Irish of Cois Fhairrge Co. Galway documented /v/ in native speakers, especially next to unrounded vowels.

You could say: Munster uses /β/, Connacht uses /v/ , and Ulster uses /w/, but that’s a rough model not accounting for individual variation, sub-diualect, and phonological environment (like whether it’s next to a rounded or unrounded vowel)