He misses the point - confiscation is unlikely to take the form of door to door raids, but rather Aussie style -
1. An order to turn in guns (possibly, but not necessarily with compensation)
2. Orders to LE that illegal possession of prohibited firearms is to be treated as a non-discretionary must arrest situation
3. Aggressive prosecution and severe sentencing, even in the absence of criminal intent beyond the illegal possession
4. Use of existing registration lists to "encourage" compliance