But why would ArchiveTeam wants to preserve the historical items in a feed if the feed does not belong to them in the first place (neither did it belong to Google)?
It's fine if people don't see any privacy implication here by submitting their reading collection. But as far as my single individual point is concerned, I don't see why I should upload my OPML for the sake of preservation. I have hard time uploading it to any other Google replacement out there trying to compete.
That's exactly my point.
There's also no telling if InoReader is open for grabbing what they've grabbed already again. Meaning it's potentially behind closed doors.
ArchiveTeam submits the data to Internet Archive, which anyone can upload and download from. This data is continously being uploaded and made public and free. See https://archive.org/details/archiveteam_greader for example.
Anyone can do anything with that data. Your OPML files are not being submitted though. That's also being said on the linked site for this item.