i don't know why but Intel considers the 82575 and 82576 to be special case drivers. You'll note that it's not in the list that Intel provided with the code I downloaded from intel.com. I searched intel.com and found this download for your driver, which says that it only works for 3 cards. (It is also interesting that it says it isn't the latest code even though if you search by product it is the only code that matches - clearly a glitch on the Intel site.) Since your driver isn't covered by the E1000e Intel code, that means it isn't covered by this kext.
But the most surprising thing is that the kext loaded at all because when there is no match, the kext shouldn't do anything and there should be no match with the 82575. Did you use the kext as is or did you modify the Info.plist? If you used it unmodified, can you find the hex device ID for your card and see if it shows in the device list for this kext?