Yeah, I've said already during the live chat that is much too elaborate a scheme to pull off in the heat of the moment. Lots of things to go wrong. And it seems to me that the idea needs to assume that RBR would have been stupid enough to have Webber fight Massa in the first place. My take is that they would have been confident that Vettel would be safe from Massa. Then Webber would let Massa pass easily and save tyres to keep Alonso at bay. We'd end with 1 VET, 2 MAS, 3 WEB, 4 ALO, and Ferrari having taken points away from Alonso.
If your scenario materialized, they would have boxed Massa or have him pretend that there was an engine issue and pull over until Webber and Fernando passed him. The suggested plan would have simply traded-off WCC points for a possible net increase in WDC points for Fernando.
Agree with the first part though, it would have been too elaborate to pull off with a non-zero risk that things wouldn't have gone as planned.