While what you say is true, Redwolf, the earlier one introduces better pronunciation, or at least an awareness of the difference, the less reprogramming has to be done later. It is much, much harder to correct mistakes further down the line.
This is a major problem of language learning in the States and Australia. Kids who learn Japanese in high school here have to be completely retrained at uni for a year before they can join the natively-trained beginners who get the right start. They have to ditch six years of incorrect learning and start all over again. But because they think they can already speak the language, they have a bigger hurdle in learning real Japanese. Their bad habits get in the way.
It would be better not to teach kids Japanese at school at all, because what they are learning is not really Japanese. My kids are already semi-fluent in Japanese. I wouldn't want them to be taught by a non-native teacher at all.
Also, the idea that grammar can be divorced from and learned separately from pronunciation may be a mistake in itself. Languages by definition are first and foremost spoken words. The grammar really comes from and only exists because of certain regularities in the pronunciation. "Grammar" is really just an attempt to formalise the spoken patterns. You can't begin to reproduce the proper patterns if you haven't learned the proper sound distinctions to begin with.
The case that comes to mind again is Japanese. Japanese people who learn English through katakana have a hell of a time being understood by anyone except other people who learned through katakana. Learning (or teaching) creole Irish is just like Japanese teaching people English through katakana - it might expedite the process but you are not teaching people the language just a simulacrum of the language, a toy model.
Sometimes giving kids toys (think musical instruments here) can encourage them to take up the real thing later on, but if the toy is too crappy it can actually have the reverse effect. Early awareness of the difference is important.
I'd have been really upset if I found out after years of study that my Irish was katakana-like, a creole. Unfortunately, like people who learned Japanese in high school here, that's the case with so many people who have been taught Irish through the schools (or glitsy "modern" Irish textbooks and media).
If only we had the resources to teach real Irish the same way. Failing that, we should be able at least to point out to people what constitutes the good stuff and what not (subjective as that may be

).