It just seems like a financially stupid thing to do. At 25% off, you'll attract those who regularly purchase it and want a little more. Which I doubt will clear stock levels in the few days they have before a legal ban comes through
If it was 40% off, Joe Regular might go 'well, for that price I have to try it!'.
I apologise if it sounded inflammatory and I fully understand that he will be absorbing a loss either way, but if he sells them at $10 below cost and gets rid of them all, he'll only lose $10 on each. Selling them for cost (let's say) will allow him to split even on those that he sells, but what if he is left with half his stock? He'll then lose everything the remaining units cost.
Best to make a small loss than a large loss.
But hey, maybe he only has four jars, I dunno.