This is a strange response. Reporting a bug is likely easier than creating and maintaining a package. It’s also the better solution for users, rather than getting website operators to install yet another lib and then remember to remove it once a fix does land.
If you need the shim anyway to fix it for your users it doesn't particularly matter to you at what point Apple fixes this. The fix will take months to percolate in the best case anyway. It seems you also need an Applie-ID to even report a defect.
So to me the unwillingness to help Apple with this is not a strange response. Especially considering Apple made Safari closed-source.
I find the response weird because the commenter had an unwillingness to do free work for a company yet publishes a package that fixes their mistake.
Writing a bug report is work.
Writing the shim is work.
The bug report doesn't fix the problem right away. The shim fixes the problem right away.
Reporting the bug will cause a fix for everybody eventually. Adding the shim will fix it for me.
If we want to be nice to Apple - and get rid of the shim eventually - sure, we write a bug report. But if we can fix it before reporting, that gets priority.
Why should anybody work for a megacorp for free?