Joke's on you; I already do shut down every PR automatically on my projects with the repo-lockdown bot: https://github.com/marketplace/actions/repo-lockdown
Making my code public at all is what costs me nothing. I am already writing it. I am already versioning it with Git. Giving you access to it is either a no-op or is some amount of public good. It can never be a negative. This is what Free Software is. Read Stallman: https://www.gnu.org/philosophy/free-sw.html#four-freedoms