Thank you for posting your question. I reproduced this on my machine with other patches that were not publicly available and the reason for this is because predictive patch will go into your scan history and check for anything that has been scanned for, but has not been installed. When our content team determines a patch is no longer publicly available they will mark it as such but not pull it since you can still install it, but you have to download it yourself. Therefore, it looks like those patches were scanned for in the past and since you have not deployed them and they can't be downloaded, they keep trying to download. Things are working as intended, but I do see how this can be a nuinsance.
What you can do is put all of those patches in a patch group and exclude them in your scans and then delete any old scans Database Maintenance - Purging or Cleaning Up a Large Database that might have looked for those patches. I would recommend deleting as many results as you can and that will at least take care of the majority of those updates showing as not downloadable.
The second thing we would like for you to do is submit a feature request here https://ivantisecurity.uservoice.com/ for a modification to the predictive patch download feature to maybe have the option to not remember scan results over a month old or something like that. We would appreciate any suggestions you can make to improve this and let me know if you make one and I will vote for it.