Well, Peter Cushing played the Doctor in a couple of non-canonical movies, but I suspect the BBC would like us all to forget about those.
There's the Valeyard, of course.
There could be any number of regenerations between McGann and Ecclestone.
Also, in "The Brain of Morbius", the Fourth Doctor is shown an image of his previous selves, including the three 'known' Doctors and several faces that hadn't been seen before. The suggestion there was that Hartnell was not really the First Doctor at all. However, this has later been explained away as being Morbius' previous incarnations, or being potential future incarnations, or... whatever the case, Moffat could now be 'unconfirming' it.
Oh, and going back to things they'd rather we forgot - there's always "Doctor Who and the Curse of Fatal Death", with Rowan Atkinson, Richard E. Grant, Jim Broadbent, Hugh Grant, and Joanna Lumley as the Doctor.
Finally, though... I'm inclined not to read much into his comments. Steven Moffat has been known to be... unreliable at times.