Huh, I haven't read Coyne's book and I just searched it on Google Books:
"Coach Stone was tough and demanded excellence from us---which is to be expected in order to make an Olympic team." (p. 139)
"Our team got the bronze, which was the worst finish ever for the United States, and Coach Stone was not happy. Neither were we." (p. 140)
"I'd had Coach Stone's voice in my head since I was fifteen, when she was first-ever U18 coach and was demanding excellence then. Over the years, she pushed me harder and further than I knew I could be pushed." (p. 141)
This is all about what I would've expected Kendall Coyne or anyone else to write about her international experience playing for Coach Stone.
Coach Stone not returning to USA Hockey is not much evidence of anything, since in recent history, you more often than not don't see anyone staying for more than 1 cycle as head coach at the international level, true for women's hockey today (though obviously not in the past - Ben Smith stayed 3 Olympics) and that's true across a lot of team sports.
I expect more of the issues of substantial concern here will have manifested in the Harvard environment rather than the international environment. Some of the pain in college may have been cumulative over 3-4 years, which makes a difference (of course not always -- Abra is a public leader of the opposition after just the 02-03 season). The power balance between her and reputable Olympians vs. her and incoming Harvard students just isn't the same. And the pressure the coach feels to keep players focused on hockey in college is just different.