This is a valid take and I actually took efforts to locate the position of the thumbnail in the video (their server is somehow slow to reach from my country, so...). It's around 14:50 and right before the Q&A.
I'm not very sure if a better (in terms of avoiding controversy) thumbnail is possible; the presentation is about a video "editor" and the only visually meaningful frames are photos of two presidents and a mix of them, so picking any of them would be problematic. To be honest why do you use those photos in the presentation after all? I do get that organizers have zero consideration about inappropriate presentations, and that's one of the reasons I don't like suckless in general.
I'm not very sure if a better (in terms of avoiding controversy) thumbnail is possible; the presentation is about a video "editor" and the only visually meaningful frames are photos of two presidents and a mix of them, so picking any of them would be problematic. To be honest why do you use those photos in the presentation after all? I do get that organizers have zero consideration about inappropriate presentations, and that's one of the reasons I don't like suckless in general.