Perhaps because this person refers to a specific Lisp implementation that runs on top of a virtual machine? Various Lisp systems since the 70s work on top of specialized virtual machines. Some current implementations, such as CLISP and CMUCL, still have their own virtual machines.
Virtual machines for Lisp are typically specifically designed for Lisp requirements. They provide the necessary primitive data types (for example, cons cells, characters and large integers), a set of commands (calling a universal function, checking data types at runtime ...), memory management (garbage collection) and other services (dynamic loading) the code). They often provide some extended stack machine.