As my Police driving instructor said when faced with a hazardous situation is a choice "either back off or f-off" was his advice
If safe to do so in other words is to leave the potential accident to happen behind you not in front if it isn't safe then back off and give them plenty of room, then should an accident happen you have room to avoid
That of course does not mean to undertake which is not only dangerous but illegal, but to pass them in lane 3 if available but only if safe to do so.
Russ