That is not personal data under GDPR.
«So on one hand it might say Macron was born December 1st 1977 (which is correct), but if you ask how old he is some LLMs might say 45 years old.»
Or it might say that Macron was born on 14th July 1977, which is incorrect. The claimed impossibility to correct a date of birth returned by the LLM is the trigger of the GDPR complaint that the article refers to.
«Also this creates a situation where all but the most powerful LLMs (and LLM providers) will be non-complaint»
Only under the premise that it is somehow inevitable to feed personal data of living individuals to an LLM for training, and that the only way to correct mistaken data or to stop an LLM from providing such data is "more power".
I reject the premise, not the least because, firstly, OpenAI (the most "powerful" provider) is claiming it is impossible. All that says is that OpenAI's platform was not originally designed with that problem in mind and that, as that of now, they are unwilling to redesign it from scratch only because some guy complained in Austria. It's basically a speedrun of Microsoft claiming Internet Explorer was an essential component of Windows 98.
Meanwhile, LLMs and other AI models are an active area of research. If OpenAI truly cannot stop their LLMs from returning personal data protected by GDPR, and honestly has no way to allow data holders to exercise their rights of deletion or correction, you can be sure that some startup will disrupt the LLM market by finding a way to do it without needing to out-compete OpenAI neither in hardware nor on training corpus size.