Those suction mounts (at least the actual GoPro ones IME) won't go anywhere if you attach them correctly and are a million times less likely to become a cabin missile during an RTO than me holding my phone during takeoff. While it does block part of the window as long as it's not an emergency exit I doubt they'd care as any smoke or fire would be visible still. As for why? Why not? I pointed mine out the window of the Eurostar I took from London to Paris and again a few days later when I traveled from Paris to Bayeux. Have I watched all 6ish hours of the video from those trips? Nope but it was interesting to scrub through them and see different part of the English and French countryside.