Do you really believe they don't have backups? Especially since it seems selling content for AI training was their plan for quite a while?
Or that they didn't make full backups a couple years ago before the protest, anticipating a lot of users would try to delete their comments?
I think the only way to truly delete anything from reddit would be living in EU and enforcing a GDPR request, but even in that case, I believe it would be very difficult to check they actually comply.
Not the one you're asking but I've been dual-booting Windows and Linux on my gaming desktop for many years, every time a build a new PC, disabling "secure boot" AND "fast boot" in the BIOS is the very first thing I do and I never had problems (I play on Linux but I keep Windows for testing in case I want to report a bug).
Fast boot is even more troublesome, since it's a Windows specific feature that allows it to not truly shutdown so it can startup faster later, but that can cause locks for other OS that won't work correctly.
In theory, Linux should be able to support secure boot (not fast boot), but since that one too was made for Windows, there are cases in which it could cause problems, I will always disable it just to be on the safe side.