If I recall correctly, you can sacrifice some corrosion resistance for a little bit of additional toughness in some steels (S30V among them), by adjusting the heat treat accordingly, but I don't know whether Spyderco does indeed do that.
A more important aspect is the surface finish. Corrosion resistance is highly dependent on surface finish. A smooth surface will always be more corrosion resistant than a rough one and finishing S30V is apparently very difficult (Ed Schempp recently mentioned that he has never been able to polish S30V to the same degree as other steels). I have therefore no difficulty to believe Doug Ritter's claim (even though for use in salt water environment my personal choice would always be H-1).
A more important aspect is the surface finish. Corrosion resistance is highly dependent on surface finish. A smooth surface will always be more corrosion resistant than a rough one and finishing S30V is apparently very difficult (Ed Schempp recently mentioned that he has never been able to polish S30V to the same degree as other steels). I have therefore no difficulty to believe Doug Ritter's claim (even though for use in salt water environment my personal choice would always be H-1).