Well implementing all the OOP semantics and such could complicate and dilute the essentials. A simpler language would also make it easier to cover more ground,

Well implementing all the OOP semantics and such could complicate and dilute the essentials. A simpler language would also make it easier to cover more ground, such as type checking. So I don't think it sounds ideal from a pedagogical perspective either, but again, I haven't read the book. Note that Lisp in Lisp (SICP) works well because Lisp itself is very simple and just the essentials. It's just one chapter in SICP.