The argument was over till he “stirred the pot”
Stirring the pot can have several meanings in cookery.
If you are making a jelly or cold pudding it will set o if you leave it alone after mixing the ingredients ideally in a fridge or cold place
However unless it is in a very hot place it will eventually set but will take much longer
That is probably what is referred to in the sentence.
If you stir a dish of simmering meat it will not affect the outcome unless you make a hole in the pot with violent stirring for hours.In which case you deserve all you get