No, a silhouette won't show in the member spotlight (it's not coded to), and users without an avatar won't show in member spotlight unless you remove the line as previously indicated.
Silhouettes show in some areas as a placeholder when no image is provided, as of 758+. If you look at your profile, your avatar is a silhouette.
If the silhouette was used everywhere it'd be quite the distraction, hence why it's only used in areas that require one to be.
Fyi, the member spotlight will not assign a silhouette to users without an avatar, the code will probably just try to load an image that doesn't exist.
