Cuz they made in wuhan.
I was thinking about this as well and perhaps they are thinking it may get so bad that they feel they may not be able to get to the store in the next few weeks or that stores may even be closed for a period of time and/or that supplies may dwindle if supply chains fail. And perhaps it's just general panic with no reason at all.
Apparently there are 142 paper manufacturers in North America.
https://paperonweb.com/ppmanf.htm#na
Allegedly, most have a plant dedicated to tissue paper (toilet tissue is a subset of tissue paper) production.