I mean, come on. With technologies beyond all of humanity's, he couldn't find a way to wriggle out of this one and "rewrite" time? 
*\*scoffs*\* definitely a plot hole; the writers wanted it to seem inescapable so that later on we easily buy into why and how 

> 
>  Rory and Amelia left the show. How it *must've been* Amelia's farewell 
> 
> 
> 

because River *had* to break her wrist *just because* they read their futures. so it seems that time *could absolutely not* be re-written.

But I'm prepared to stand corrected. Anyone?