Just my two cents, I just checked this PR you mentioned and don't think they threated you as you think they did. Just read what they said slowly.
They just ask you to open another PR with some more information, such as why did you make it, what does it solve, why did you make some specific decisions etc. You can select the same branch in the new PR.
Making changes to PR's is normal and maybe (realistically) even unavoidable. Developers who work on a project usually have specific ways how they'd like to see code in their project and other developers should adapt this. PR's are usually the way to go to discuss things that were changed as well.
None of my PR's have ever been merged instantly, there is always feedback and things need to change. For example, look at this PR or this PR, feedback, changes, changes and in some cases even more changes. And that's good, if they merge everything without hesitation, the project wouldn't be as it is now and would get a bad reputation.
At the end, everyone is happy. But, it can take a while. Patience and being comfortable on receiving and process feedback is the best weapon you can have in these situations.
P.S. Downloading files in a Docker container from pastebin.com (an external provider) is just not safe for a project as this (it can harm the security if the service is being taken over in the future, down or is hacked showing different code). This is what they meant.