All of this holds up until you remember that Bitcoin is fungible and take these items into consideration: 1. There is no logical relationship between address A

All of this holds up until you remember that Bitcoin is fungible and take these items into consideration: 1. There is no logical relationship between address A that spends to address B. 2. A could be part of the same wallet as B, or not. 3. A or B could be undisclosed addresses of merchants, or unrelated parties entirely. You may have to ask, and they may choose to tell you. Defeating your inferences is trivial. A blockchain analysis may reveal that A sent to B, who sent to C, but there is no logical relationship between A and C based on this transmission alone. Moreover, A can send to B, B' sends to C. You derive no information.