They do explicitly address that - as you yourself quoted above, travelers "... should plan for this dilemma ahead of time", i.e. depending on their personal situation, before the trip they should either be prepared to comply (ensuring beforehand that no incriminating information is accessible and full compliance, if needed, won't endanger themselves or others) or be prepared to refuse and face the consequences; if they believe that they are likely to be inspected for some reasons (the vast majority of travelers are not) then this includes making plans on how to mitigate the effects of not getting across the border.
If you want to go to America you have to comply. If you are stupid enough to have incriminating information on devices you are carrying across the border then you obviously refuse.
The choice is just whether that privacy is more important than getting into America to you.
1) comply - possibly incriminating yourself, endangering your security and anyone you have contact with
or
2) refuse, get arrested, harassed, deported and probably placed on some kind of watch list as a known troublemaker
Which should you choose?