I'm far from being an expert either but I did find a current definition of stainless steel here
What Is Stainless Steel? .
By the looks of it the Patent Cobalt-Chrome Steel has a chromium (Cr) content of 11.75 - 13.75, which I take to be a percentage, and meets the minimum 10.5% chromium content level in the definition of stainless steel.
To positively know if the razor is stainless you would have to know if they used the Patent Cobalt-Chrome Steel in making the razor. OTH you could have the blade tested but I guess that would involve destructive testing and not really wanted.
Chances are looking pretty good that it is a stainless steel razor but that is just based on assumption.
Bob