The main reason is that it takes a lot of time and energy to review pull requests—especially for this kind of software. For example, I have a server that continuously runs Litestream on a database that's constantly producing load. Every time I make a change in how Litestream works, I create and push up a new build to that server and run it for at least 24 hours. After that, I review metrics about performance and throughput and go through the logs to check for any abnormalities. Finally, I have a separate runbook that I go through for manual testing every CLI command and their various options. It's a slow process but it helps catch weird bugs that aren't apparent from automated testing.

As for the license, yes, the PR author agrees with the license but it makes it harder in the future to change the license and then I need to maintain a Contributor License Agreement (CLA) which is more work. I don't have any plans to change the license but I also don't know if that will change in the future.