Well, since your conclusion that I am in then wrong seems to depend on the idea that words like help and single mother have some different meaning other than what they clearly mean, I find your logic and reasoning spurious at the outset. And I hate to break it to you, but coaching at an all-comers club that meets one day per week and doesn't charge anybody, and agreeing to work individually with someone who seeks you out and is serious enough that they do offer to pay you, and presents a sympathetic case for needing your help isn't "cherry picking."
While I could argue that even under your misguided analysis - the "destruction" I caused (note that the quotation marks work much better around your words than mine) by hurting the coach's feelings was of course far outweighed by the financial benefit to the athlete and her family, my actual point is that, at least in field events, (or at least the jumps) I think it would behoove people to consider the relationship between the athlete and head coach more like that of a clarinetist or flutist to a band director, who should in fact not get his feelings hurt at all if the musicians in his band seek out private lessons ( particularly in the case like this one, involving a family with financial needs seeking a scholarship to college for their individual skill and accomplishments.)
Just BTW, the musician / music lesson analogy isn't mine, I got it talking with Pat Henry at the NCAA meet last year.
Since the originator of the thread asked if there were occasions when an outside coach wrote training plans for high school athletes, and the thread contained repetitive stories of incompetent outside coaches ruining their athletes performances by sneaking around and interfering, I thought my contrary experience might provide some counterpoint. Your criticism, which is based upon mischaracterizing my situation as being the same, rather than different from, those other situations really doesn't advance the debate.