There may have been a nonzero chance of it starting a fire, since the article describes some printers as “tearing themselves apart”, which could conceivably have included wiring damage or hot things landing outside the printer on flammable material.

Also, since it seems to have been printing copies of previous prints, um, well . . . some people do print sex toys. I can see how explaining that one to your eight-year-old or your mother-in-law, if they find it first, could be considered a nightmare.