because the words "responsibility" & Sony don't work in the same sentence
abobe - to be fair - have made hyphenation controllable, though they don't bother to document it, so you need forums like this to learn the commands from.
it' s Sony who have not bothered with a user preference, so you have to do it before side-loading the book - and if the book is DRM'd then you can't do it al all.
and as Sony are quitting the e-read market they won't ever fix it for you- .
So use the given workaround. you need to add this to your CSS:
body {adobe-hyphenate: none;}