Category A: scrap only. For cars so badly damaged they should be crushed and never re-appear on the road. Even salvageable parts must be destroyed. Source: RAC website Doesn't that mean you couldn't even make a track bike??
Yes Cat A's should never appear, either as parts or as a whole. This could be a reason why he's took the numbers off. Or it's stolen.
Is it more likely that Cat As are fire damaged as its likely to damage other and non mechanical parts? There for total salvage but a Cat B is more mechanical there for only the chasis is normaly scrapped and 99% can be recycled.