Hi Lowmick,
Agreed, without looking am sure you are correct with regard to the fact it does not meet the definition of a multi-pilot aircraft according to category (C525/C525A), but the Citation 525(A) does meet the requirements for hours counted towards the issue of an ATPL (albeit you cannot unfreeze in a Citation 525(A) as per your previously mentioned statements) as a multi-pilot aircraft when operated in accordance with EU-OPS Subpart N, Ops 1.940 (composition of flight crew), Para. b (IFR & Night ops), and as approved by the relevant authority in which the aircraft is registered and/or operated as part of an AOC operation (UK).
Someone please correct me if i'm wrong, may well be off in my interpretation.
F/O