@jumbanho well right.

I don't know what your point is at this point.

You asked for a study looking at indirect measures of causality, which this study did, and then you asked for one that was even less direct, for some reason, and now you're describing how RCTs are indirect, which sounds to me like proving that the study did what you're asking for...

It just sounds more and more like you really just want a study to confirm your biases.