You absolutely did not understand how the code from my previous answer works, yeah? The PHP ternary operator $result = $a ? $b : $c works the same way as the following construction:

if ( $a ) {
    $result = $b;
} else {
    $result = $c;
}

So the whole idea was to check if the get_user_meta(get_current_user_id(), \'last_name\', true) function returns an empty value. When you change it to

($username = get_user_meta(get_current_user_id(), \'last_name\', true)  . \'</a>\') ? ...

you break the whole logic, because that

get_user_meta(get_current_user_id(), \'last_name\', true)  . \'</a>\'

string would never have an empty value (that should be quite obvious, even if the get_user_meta() function returns an empty value, the whole string would be equal to \'</a>\'). Use this statement:

return \'&nbsp;<a href="\' . admin_url(\'profile.php\') . \'">\' . ( ( $username = get_user_meta( get_current_user_id(), \'last_name\', true ) ) ? $username : ">Noe Name [edit profile]" ) . \'</a>\';

Update

If you want to work with several user meta fields, I recommend to use get_userdata() function:

function colaborador_nome($atts)
{
    if (is_user_logged_in() && !is_feed()) {
        $userdata = get_userdata( get_current_user_id() );
        $username = trim( implode( \' \', array( $userdata->first_name, $userdata->last_name ) ) );
        return \'&nbsp;<a href="\' . admin_url(\'profile.php\') . \'">\' . ( $username ? $username : ">Noe Name [edit profile]" ) . \'</a>\';
    }
}

I still don\'t understand why the shorthand form of ternary operator doesn\'t work for you, using it would help to simplify the return statement to

return \'&nbsp;<a href="\' . admin_url(\'profile.php\') . \'">\' . ( $username ?: ">Noe Name [edit profile]" ) . \'</a>\';