Well, this is true, because as owners can do whatever they want. But Reddit's 'product' is community, plain and simple. So firing a loved admin is essentially taking away a bit of the reason for being on the site for many of the users. I think at the heart of the discontent is the tension between a grass roots community and the fact that there is ultimately a autocratic power over it all. In other words, the firing is a reminder to the users that they don't have control over their community.

This whole incident is just growing pain. Ultimately, they will form or join another community where they don't need a paid liaison to the AMA person. That community will have more self-governance. Additionally, that community may self-fund itself, and the destruction of the the community in the interest of monetization will be less easy. There is likely a lot of work that needs be done to enable that type of community, both technically and socially.