I think Lisp has too few symbols. I completely agree with the author on this.
I think there's a balance where we use enough symbols to make the structure of the code stand out but don't try to make everything into a symbol since the language is essentially extensible by the user in building the tower of concepts.
Next question: is operator overloading good? It lets you write extensions that feel like they are part of the language, but it also makes the code difficult to evaluate mentally since you might not know that an operator means something different now.
I've always found it rather annoying to use collection APIs in Java, or big num libraries, since you have to call long-named functions for simple operations. In C++ you can overload operators to concatenate, iterate, and inspect collections. But this can be misused (in C++, Lisp, and other languages) to make code harder to figure out.
Math notation, though, does have overloading. "+" is not just add two integers, it can be used for set operations sometimes. Also some notation is used differently in different disciplines, like math-like notation in some computer science papers (e.g. describing a type system or Lambda calculus evaluation) look similar to operators used in logic or calculus but mean different things. So operator overloading is common. Is it good?