I think it can be simpler than that. If a piece of code is going to do a velocity calculation from motion estimation between two frames it should expect to get new data every 1 / FPS seconds. A local clock could help validate that. If data comes too fast or too slow within some tolerance then the system could signal there is an issue. If the images have time stamps it could check those too.

Now you’d need to hope the inertial guidance is good enough at those altitudes. The article says it doesn’t use image based calculations for landing due to the possibility of kicking up dust.