simple

You really don't need to care about whatever's happening with Threads as a casual user

Mostly aesthetically, but also since Linux Mint is a very stable distro updates are usually slow and the packages it uses are often a little outdated. If you're the type of person to want to update to the newest thing as soon as it's out, then it's probably not for you.

Manjaro and Ubuntu have never really had perfect out of the box experiences imo, and as usual the Linux community loved to recommend bad starter distros. Even Fedora has some eyebrow-raising stuff like forcing you to manually install Nvidia drivers through the command line.

If you want something that "just works" I'd highly recommend ZorinOS or PopOS. They've got good defaults. Linux Mint is also good, but it does feel a little outdated.

But does he have the 5 certificates required to qualify him going to the interview?

It's a known issue with Lemmy, it should be fixed by next release.