Its an airline specific policy, and outside of a 787 if you have an event that involved an impact with the ground of more than about 3G you will find that all of the window shades in the cabin will self close except for the ones on the doors that are push down to open and pull up to close (funny that...)

I unaware of any crash/event where the NTSB or any other safty board cited the blinds being opened or closed as having an impact to any specific event outside of a negative one. E.g there have been a number of ill advised and uncommaned passenger led evacuations of aircraft at gates due to non-harmfull fireballs from the engine starting process.