In the two-party case the likely reading is the classic arrangement: each party holds an input, one of them also garbles, the other evaluates, and the result goes to the party or parties entitled to it. The assurance question is not whether the protocol is clever but whether the same organisation controls both roles in practice, which would remove the independence the model assumes.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.