I have found a major B/C API issue here:

1. This is inconsistent/incompatible with declarations of parent classes Table and TableInterface, and thus breaks the defined PHP interface.
2. More importantly, this also breaks B/C, and Community Builder when saving user profile in frontend, when changing e.g. just the name, but keeping password same (and thus the corresponding $user->password null, which generates an exception and corresponding fatal Error "Column 'password' cannot be null". And an ugly workaround would mean to read the hashed password and re-store it on update.