Hi @benjaminmi3 ,
You can try something like below with your segment and OOB segment "All Visits",

Here I've put the segmented audience (Non-Purchasers) and entire audience (All Visits) side by side with the needed metric applied and then using context menu created an project only metric by subtracting the two columns,

This might not suite all your reporting needs but this seems to be the best alternative to creating another audience.
Cheers!