So I have contacted Cinelli and await an answer. For the time being I have calculated the Stack and Reach of the Kestrel:

Kestrel Size 54: Stack 52, Reach: 39.7

Cinelli Size M: Stack: 54.8, Reach: 38.7
Cinelli Size S: Stack 52.2, Reach: 38.3

The Kestrel's Stack of 52 is already at the upper limits for me and therefore a stack of 54.8 and like I have said a virtual seat-tube length of 57.2 is just too big. I would sacrifice the slightly shorter reach as that can be more easily accommodated for.

It is clear that I am over-thinking this, yes? This is because there are no dealers anywhere around which carry this bike and I cannot simply go try it.

I am still considering Giant and Scott frames with similar specs. But this Cinelli is very enticing.