Actually the math lies in looking at the reward chart. With SPG, you redeem rooms for the following amounts of points:

2k,3k,4k,7k,10k,12k,16k,20k,25k

depending on the hotel and peak/low season if applicable (see reward charts for more details)

where with PC it takes a min of 10k points for a lowly holiday inn express on up to 30k for a night at an intercontinental.

That is where pinniped is deriving the value per point from, based on how much you would spend for the hotel compared to its point value. Last year, for 10k points (now up to 12k points), I stayed at the W Times Square when rates were over $500 per nght. Again, 10k in PC gets you a night in the lowly holiday inn express. The lowest SPG properties are 2k per night on weekends.

Also, this does not consider capacity controls. I am not sure about PC, but as far as I know, SPG is the only hotel program that does not implement capacity controls - if there is a night available, you get it. You can also cancel the rez up to the night before (or possibly day of, I cannot remember).

I do not think I would get much of an argument on this forum in saying that 1 starpoint is worth much more than 1 PC point.