i think that's a reference to the fact that Mathematica uses M-expressions and operator precedence. it doesn't look like lisp, but if you FullForm an expression you will see that it's all just M-expressions.

that said, i think it is lisp-like as a design choice. the Mathematica language itself is more raw than even lisp -- you can take the language in different design directions. Wolfram chose to include lisp aspects