I know, but that is not something which would be visible to passing burglars. The fact, if it is a fact, that they tended to blow open as well is more important because that is visible and, as I said, explains 'Guede's' choice of window.
My point is that the shutters blowing open, while possible, is not really a likely logic point. Given that the shutters did not lock, did not close easily due to warping of the wood, and the testimony of Filomena that she does not think they were closed all the way, it is entirely possible for Rudy to have seen them ajar, even a little, or simply be aware of how shutters of this type work in Perugia. It is my experience that exterior shutters are rarely used as a crime deterrant anyway, it is the interior versions, and/or the window itself. Shutters are easy to break open if need be.
So although it is likely that the wind could have opened the shutters, it is really not necessary, IMO, to any theory of what happened.
I was giving her too much credit, mayhap. Well, is she still a guilter?