Linus's idea is mentioned in ESR article, which even represents the main difference between him and RMS. First of all, RMS thinks that non-free software is immoral, so users should morally resist non-free software and use free software. The ESR article mentioned that Linus believes that users need better software, whether it is free or not. Open source is a way to build better software, so he insists on open source. Thus, ESR put forward the slogan that "it is better to use, so open source" is better than "because of morality, so software must be free".
For a long time, Linus' responsibility in Linux development is actually code review, in other words, QA. In the collaborative work of thousands of people, he is responsible for ensuring that the quality of Linux code reaches the expected goal.
So, perhaps the core idea of Linus is to make high-quality software.