Not really. They say that having random (ha) people in the picture improves the entropy, but they don't address the possibility of people using it to gain information about Cloudflare's entropy pool.

presumably if you set up camp with a camera in their lava lamp room, somebody is going to raise some eyebrows.

Not only that but your cameras are going to have to be precisely in the same place as theirs, with an identical view and be identical models with identical sensor variation, dust on lens etc etc etc ad nauseam.

As you say, that might raise a few eyebrows.

Wouldn't you just cover their camera with paper or some other known pattern, if you were going to try that?

Ooh! Can you shine a laser into the camera to blind it? Burn the sensor to a crisp and then let that seed the CSPRNG!

Great way to test how quickly you can get thrown out by security guards