The biggest mistake, Sam had done is to put his view aggressivly to his manager who he feels not capable or not having enough qualities to lead him. Though sam view were correct practically and good for the organization; he faced severe problem by going against his manager. Office politics is not new to corporate world.
What Sam had not done to avoid such problems and stress, and still express his feeling is an art, art of conversation.
In start of career when you are fully charged and you see world black and white and your energy wants to change the world on your will, oftem makes such mistakes. I have not seen any ideal orgainzation, in short where ever human are involved, such things bounds to happen in many ways - a promotion stuck, not getting credit of your work, stress, pressure etc.
I would like to make it clear that I am not at all against that you should not express your views, ideas and queries, the only thing, you would have to tweak the approach to make it assertive rather than aggressive. And make sure that your words does not show disrespect in any way.
Having a good relationship with your peers and managers always makes things easier for you to communicate your perspective and who knows you may get appreciation to present your views and ideas.
Keeping silent and noding your head to everything, wont allow you to climb up the corporate ladder but at the same time presenting your views and ideas should be in assertive manner. And never forget to show respect to each individual.