I love that they have an image of the floppy disc with the source code! I wonder if that's still readable?
My thoughts exactly. And if it's not then it's just a random floppy disk. Even if it did have the source code it's a little unremarkable without being able to read it.

The plaque above the disk says it is just 99 lines of code, I wonder why they didn't just print it or engrave it onto the plaque.

It seems the original source code is not available online, though there is a decompilation.

https://github.com/arialdomartini/morris-worm