I forgot Destroy Windows 10 Spying had an option for re-enabling updates, which means I went through way more trouble than I needed to.
But god, DW10S is the only thing that makes that OS usable for me.
Meanwhile I had the security update taken care of on the Ubuntu Mate laptop within 5 minutes.
I think I'm starting to genuinely understand Linux snobs now.
@polychrome I haven't heard about it until now. Sorry. I might need to look into it..