No, in that context, 0 has the meaning of "none of the above" referring to the flags, which means "process as a command", not "as if typed in editbox".
The docs for WM_MEVALUATE imply that 0 is an option. Therefore if 1 and 0 behave the same for WM_MCOMMAND, the docs should indicate it, especially given the name of the message constant and the heading of the section.
Either the behavior should be changed or the docs should. What is the appropriate forum for reporting discrepancies in the docs please?