::::: (1) I actually don't think that every instance of sex between an 18 & 17 year old is child sexual abuse  hardly any is probably more like it.  But, leaving aside the chasm of difference between that scenario and what Goldschmidt admits to doing, I am not a reliable source for what that term means (& neither are you.)  I'll take the APA's word for it, since they're experts and their work is well-regarded and rigorously reviewed, as is the work of the National Library of Medicine and all the others I cited.  If you think your arguments about whether 40-year-olds are engaging in child sexual abuse when they have sex with their childrens' 14-year-old babysitter actually hold merit, then go try them at the child sexual abuse article.  Until the meaning of the term changes, such "relatioships" will remain child sexual abuse, regardless of your opinion or mine. 
 ::::: (2) Your argument is yet another quibble  A source says that Goldschmidt sexually abused a 14-year-old girl;  The definition of child sexual abuse encompasses the sexual abuse of a 14-year-old girl.  must those exact words be used verbatim in order for you to accept the denotation of the term?  Child sexual abuse occurs even in the midst of the loving relationship that can only exist between a 40-year-old politician and his kids' 14-year-old babysitter. 
 ::::: (3) Goldschmidt personally admitted to fucking a 14-year-old when he was more than twice her age.  He didn't take her out to dinner & a movie;  He took her to the basement and fucked her while she was still a child.  Since that (by definition) is child sexual abuse, no further research is necessary.  He's already admitted it.  ''''