Curiosity got the better of me, so I dug out the opener. As you can see it is old and somewhat tarnished, but it is clean and the cutting wheel still sharp.
As I suspected the lip on the top of the can was too high for the cutting blade to engage, but I flipped the can over and was able to cleanly remove the bottom.
Now I have to eat 120 g of Russian fake salmon roe for supper!