Groundloop - you are correct in stating that an FNPT2 MCC must be a turbine powered, pressurised, multi-engined aeroplane.
It may be generic, with performance and handling "typical of it's class" or based upon a particular aeroplane as most are in which case it's performance and handling are expected to match that aeroplane to the standards detailed in my earlier post.
Therefore a Seneca may not be used for an MCC - but a Kingair, for example, may.
Of course, if an FTO has access to a full flight simulator then that may be used, too, although the QTG standards required are little different in practice.