When you make an absolute claim like "Learning new syntax really isn't hard." you're really saying "I find it easy therefore everyone else must too." That's poor quality thinking at best, and actively toxic to your peers at worst.
In my twenty+ years as a mentor to developers I've learned that objective statements about what is and isn't hard in programming are always going to fail when it comes to some set of devs. Some people find it trivial to move from one mental model to another. Other people find it really hard. This is true for every aspect of development - there is nothing that everyone finds easy or that everyone finds hard. If you don't take that in to consideration when you talk about programming you're always going to be failing at least one group.
Describing syntax swaps as a "move from one mental model to another" is intellectually dishonest.
Of course there are limitations to how functional you can really be in JS; that said, I like the idea of introducing some basic concepts with JS. If people like the idea, they can pursue a "functional first" language.