I figured that part is obvious. Also, the Din would still apply to ZK, but that’s a different story.
I said only if it’s gooey, since the Gemara was specifically speaking of goo. I think Rabbeinu Chananel is more clear about the idea being that it disgusts people to be near him. Dried goo might also be included. I only meant, as opposed to ketchup or grape juice.
I was always told that it applies to all Yeshiva, or learning, people.