Well, it is partially his mistake, which he acknowledges:
> I am certainly not innocent here and some mistakes were made on my part. [...] To this end, having encrypted access keys or excluding configuration settings from GitHub would have prevented the AWS charges - and this is certainly the approach I would take from now on.
> I am certainly not innocent here and some mistakes were made on my part. [...] To this end, having encrypted access keys or excluding configuration settings from GitHub would have prevented the AWS charges - and this is certainly the approach I would take from now on.