This was fun and more fun because the first start of my research was done on my phone as I was eating in a Chinese restaurant.
The update by @mahdiyari worked. My mom's (@dagmardeeke) account stopped following the trail from @aliento. Her last vote following the trail vote was on Saturday, as you can see here. The two recent votes were manual.
It's good that this was solved because it would have affected many users. Now if the user has not given the posting authority to @steemauto, the trails will not be activated.