The package manager shouldn't matter in the least for a 100 level CS class as you're supposed to be learning the fundamentals instead of just bringing in left-pad, and the like. I don't think I used an external package in any of my CS classes (in any language) until maybe senior year. We used C, Java, and Python for various classes throughout my time. Oh, and one class used PHP.
What I wonder though is, what is the goal of the current class? If it's about teaching OO fundamentals, I can't imagine JS would be a better replacement for Java than Python. If you're just trying to teach concepts, sure JS is fine, but it just seems like Python would be all around better for instruction than JS.
I admit that for classroom exercises the package manager isn't a huge draw, but when someone learns some JS basics and they want to try to make a real thing, the fact they don't have to move to a new ecosystem to get libraries keeps the momentum high.
What I wonder though is, what is the goal of the current class? If it's about teaching OO fundamentals, I can't imagine JS would be a better replacement for Java than Python. If you're just trying to teach concepts, sure JS is fine, but it just seems like Python would be all around better for instruction than JS.