Besides, you could also say that 100% of code is generated "by software" no?
Microsoft has humongous amounts of source code in their repositories, amassed over decades. LLM-driven code generation is only feasible within the last few years. It would be completely unrealistic that 30% of all of their code is written by LLMs at this point in time. So yes, there is something in his quote that is intentionally misleading. Pick whatever you think it is, but I'm going to say that it's the "by software" part.