When I need to create scratch files I usually operate in /tmp. Almost all directories there that I saw were using randomized paths (e.g. UUIDs). I guess this is to prevent problems mentioned in the article. So, I believe this would be a vulnerability of snap, not systemd.
I use Fedora where /tmp is created as tmpfs, which lives in RAM and is cleared when the system is shut down. I wonder what's the benefit of Ubuntu's approach.