She was sincere. One of their first missions together just the two of them after Antonin finally believed that she was capable of going out without his supervision, she and Thorfinn encountered a large group of Resistance wannabes. While certainly not nearly as effective and dangerous as the actual Resistance, the odds were not in their favor. Thorfinn taught her the very important lesson that sometimes it was better to distract one's opponents and run like hell than it was to stay and fight. She closed her eyes just as a spell brighter than a hundred lumoses shot out the end of Thorfinn's wand to light up the entire flat. None of their would-be assailants were prepared for the sudden onslaught of bright light in their eyes. Shouts and groans from all of them proved that it worked. Hermione created a shield large enough to cover the three of them as they ran out of the flat with half-blind wizards trying and failing to hit them with various spells and curses. As they ran to the lift, Hermione sealed the door leading to the stairs shut. They wouldn't be able to run after them immediately when their temporary blindness wore off. Seconds mattered.