I don't see why not, as long as it isn't too soft a pull, and you aren't expecting a huge snap.
Disclaimer: I am not an engineer, and I've never made a knife.
If you think of the parts of the blade tang that are in contact with the backspring, there are two corners (at least on a knife with half stops) one corner moves the backspring from the closed position to the half way point. Then the other corner moves it again to snap the blade fully open. I imagine the tang could be shaped in a way to give less resistance during the first part, and more during the second part. Almost like a half-cam tang?
Someone please feel free to correct me if I'm totally off the mark.
No, you are not off the mark at all!
With modern computer machining centers, it's very possible to make asymmetrical tangs.
To some degree, I think Victorinox does this. Most Vic SAK's seem to have less pull on the first 1/3 arc of opening, than the first initial amount of force used to close the knife from fully opened. At least there seems to me to be a bit of a difference in force. It would be interesting to make a knife with an asymmetrical tang. I've done it with a very fine jewelers file on the tang of my Case peanut to make it easier to open for this old man. I rounded off the inner corner of the tang that is in contact with the back spring when closed. It did make it easier to open, but still had good snap.
