Doesn't really matter why he's biting. If either handling or spraying ticks him off, the best way to treat him is to do it in a way that lessens the chances of you getting bitten. Hence why I suggested putting the snake in the bathtub and lightly spaying him.
Reptile Spray is made by Natural Chemistry. I am impressed that your Petco carries it, lol. But that is the same stuff sold by Reptile Basics that I suggested. So it's fine to use. If you can wipe him down with the paper towels and not get bit, that is the best option, but you can spray it lightly directly on him too.
Frankly, I really think that line on your snake is a section of split scales and not a cut at all. If you were to pull it gently apart, if its a cut, it would look like a wound - raw flesh and at least a little blood. This appears to affect just the outer layer of scales. I'd have to see a clear, detailed, and close up picture to be sure, but this is what it appears to be to me.![]()