My experience is not much different than yours - but it still doesn't change the point I was "trying" to make. The right thing to do is defend the rights of others - but it doesn't preclude the right of others to say "no thanks - I don't want you to speak for me". I believe it's a mistake to automatically presume that if someone objects to me speaking on their behalf that blame *must* be attributed to someone - sure I'm happy to hear their opinions. It's a stock phrase but true none-the-less "you can't please everyone, the best you can do is please yourself".
There is no stock reaction that will please everyone - sometimes doing the "right" thing means eschewing an expectation for respect and/or credit. My personal belief is that the right thing to do is usually, do something.