I believe in gay marriage but I also believe in peoples right to oppose it, this whole thing is shameful.
Whether or not this is the right call for Mozilla is up for debate, but whether his rights were infringed certainly is not.
However, would I be correct in saying that his rights are not being infringed by having people (both internal and external to Mozilla) call for his resignation because of his beliefs, and his contributions to causes which are actively damaging to some of those in the community? Especially in the case of Mozilla, who rely heavily on volunteers, the opinions of those connected but not necessarily employed by Mozilla should be important.