Safe programming using marker interfaces compared to the Liskov replacement principle

Question

I know about LSP and why the following code gives:

PHP Fatal error: declaration UnauthenticatedUser :: executeCommand (UnauthenticatedCommand $ c) must be compatible with User :: executeCommand (command $ c) in the file /tmp/test.php on line 13

However, I would say that the two interfaces Commandand UnauthenticatedCommandare equivalent (since they are the only marker interface).

Given these facts, what would be a pure approach ^[1] to make it impossible for a user who has not passed verification to do anything else UnauthenticatedCommand?

<?php

interface Command {
}

interface UnauthenticatedCommand extends Command {
}

interface User {
    public function executeCommand(Command $c);
}

class UnauthenticatedUser implements User {
    public function executeCommand(UnauthenticatedCommand $c) {
    }
}

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^[1] pure meaning, not using introspection, neither programmatically nor with engine support ( instanceof).