I wondered if maybe CM stood for Claude Mabillard (from B&M), but I'm not so sure, given that (A) Toxicator isn't a B&M ride, and (B) I think that Claude Mabillard has retired (although so has John Wardley, I guess).
I'm also a bit surprised that:-
1) Alton Towers didn't produce any "Day 1" Toxicator merchandise, that would only ever be sold on opening day; granted, it may be quite expensive to produce, given that - unlike, say, an Xbox - it probably wouldn't sell in large volumes, but I remember that Thorpe Park handed out "Day 1" certificates for Hyperia last year, and AT could probably get around it by only producing a limited amount and/or offering pre-order discounts (they could even create the full 'Day 1' experience and offer sewage-themed cologne

).
2) Toxicator has 19 riders per row instead of an even number such 18 or 20; I may be wrong, but I would assume that this increases the chances of empty seats at the end (hence the single-rider queue, I guess). I think that Ripsaw had 20 per row, so I'm not sure why the capacity was reduced (maybe to increase the seat size for larger riders?).