I thought the 787 had automatic switching to an AOA display in event of unreliable airspeed ?
If the AIR DATA/ATT selector is in AUTO and either the PITOT or STATIC sources disagree such that the output from the ADRS is not trusted then the EICAS message NAV AIRSPEED DATA (in the case of pitot problems) or NAV AIR DATA SYS (in the case of static problems) will display and the PFD/HUD will display AOA airspeed (NAV AIRSPEED DATA) or display AOA SPD airspeed AND GPS ALT altitude (NAV AIR DATA SYS).
If the ADRS and IRS calculated speeds disagree you get an 'UNRELIABLE AIRSPEED' EICAS and you DO NOT get automatic AOA airspeed display.