That was true at the moment they were released. The author may change their mind later and remove the download link for some reason. For example, Staff of Ages and Midnight Sun. People who already have the patch can still manage it with their ROM manager, but the new distribution is not accessible.
Another case is the author distributes its work online, but doesn’t allow redistribution for some reason. For example, devkitpro and UT. They usually build their own sites so you know.
Some authors may post a thread on the forum, but you need to join a private chat group like discord server to get the patch. It is still available, but with quid pro quo. Therefore the database is a superset of patches available unconditionally in public.
Notice the keyword unintentionally, which means that is dead due to some unintentional reason such as dropbox link is broken. If the author removes it on purpose, it is the author who will disagree.
The database is for ROM manager like OfflineList, so the access problem is not considered. It shouldn’t contain any content of the patches. Therefore I don’t need to care those problem.
It is also a policy to protect the database. The authors have the copyrights of the patches they release, just like Nintendo has the copyrights of the games it release. Nintendo can take actions against websites providing downloads such as emuparadise, but they cannot take actions against websites which only provides work index such as OfflineList.That is the same here. Of course, the authors may not really concern whether you distribute them, like the Nintendo doesn’t care about the old games sometimes either. They don’t take the action, but they have the rights to do it. Your assumption may be reasonable, but I think it is important to avoid the risk for a huge database with so many works.
However, I don’t object to building such a repo. I only give my advice.
If you want to make a website to provide visiters with download links of the patches, you need to consider that.
I suggest to include additional extra info if you still want to redistribute the patches anyway. At least Readme and Credits should be attached. I can create patches again with patched ROMs, but I don’t have those text files, so you still need to download them by yourself. Even if you download all patches and reupload them to your website, how will you maintain it later? I think it a better way to set up a unified uploader and let the authors add their work to it by themselves, just like Japanese hackers.
Just imagine 5M per patch, then 1000 patches = 5G, and the .git folder will double it at least, then 10G+, it will break the limit of free git repo. I think it is good to let the authors to manage their own patches.
Another point you need to consider is the influence of the outdated information. It doesn’t harm if I didn’t update the checksum in the database, so the management is easy. However, if an author release a new version but you didn’t update your repo in time, visitors may download outdated patches from your website, which may confuses the authors and users.
Another case: the author released a new update with BREAKING CHANGES such as save area hack. Then users download the new patch from your site without reading the warning info or migration guide in the post, then their game save are broken.
At last, I really suggest people to put the link to the latest patch in the 1st floor of the topic. I will skip some hacks which are only accessible in discord servers or more effort needed to access. I won’t go through all floors to check the latest one.