Perhaps the simplest way to make it clear that libertine-launch is not a regular user-level command-line executable would be to move it out of $PATH and put it in /usr/lib/libertine (for example).
Perhaps the simplest way to make it clear that libertine-launch is not a regular user-level command-line executable would be to move it out of $PATH and put it in /usr/lib/libertine (for example).