...a judgement call about whether you think their beliefs are so far from your own that nothing productive can come from sharing a department with them.
it's a different (and less objectionable) type of discrimination.
Is this what we really want? A society of distrusting, hating separatist camps that vilify and exclude each other? Using organizational authority to actively punish "thoughtcrime" should be anathema to fellow liberals and those who espouse humanist values. However, there is (and always has been) a collectivist/identity/responsibility camp who thinks such authoritarian stances are ok.
A tolerant society needs to tolerate the free expression of dissenting and even reprehensible speech. A tolerant democratic society should tolerate legal political expression. As much as an enlightened company should have room for projects to experiment and "fail fast," a society should afford its citizens the opportunity to choose "the wrong" side. Really, the whole point of a democratic society, is that there's no one entity above imposing their idea of right and wrong over the populace.
Collectivism isn't evil and it is a deep part of what it means to be human, but it can't be allowed to trump the rights of the individual. People are best protected and served when collectivism and individualism are in balance.