No, he is fine with me having remote access, it's just that he lives in USA and the internet there is so bad (not everywhere, but where he lives there was only AT&T 2.5Mbps DSL and "12Mbps" (it wasn't) Comcast.
So the remote option technically did exist, and if my dad was gonna die or something if we didn't recover those files, I could have done it. But there was like 20-30 second menu latency with remote access (partly Apple's fault, the Windows machine is 5x better with the same connection, but it seems macOS can't forego its stupid animations no matter what).
I didn't mean to continue pushing you on why you didn't restore the backups, just making a general suggestion. As technical people we've got this tendency to think that we can set up systems for people to take care of themselves and then walk away. And that's great, but sometimes you just have to stay fully involved and take things over.
On the technical side, it's probably because RDP is well optimized. There has got to be something for Mac that works similarly well, but I can't give you any pointers. I was dealing with DSL as well (6M/384k), so ssh was an advantage.
Also, although I recently moved off of Mac to Linux for most desktop computing, I think I tried every single remote desktop solution for macOS over those years.
The best thing I ever found (in terms of being able to remote desktop into a 5K display and have usable latency and at least eventually show the screen at full resolution) was AnyDesk.
For my last year on the Mac, that is what I recommended for remote desktop. (It does work on Linux too, but on Linux I find xrdp works fine, just like on Windows.)
One tip: If you are connecting from macOS, using Microsoft Remote Desktop, that app crashes with 6K and 8K screen sizes. But there is an app called Royal TSX which can be an RDP client, and it handles those resolutions fine.
So the remote option technically did exist, and if my dad was gonna die or something if we didn't recover those files, I could have done it. But there was like 20-30 second menu latency with remote access (partly Apple's fault, the Windows machine is 5x better with the same connection, but it seems macOS can't forego its stupid animations no matter what).