Unity is merely an instrument that can be used for good or for bad. In itself, it has no intrinsic moral worth. It is not a value. It can at best be a precondition for pursuing some collective goals of a herd*. It is these goals that must then be examined for their moral worth.
I would argue that it is desirable -- even a moral duty -- of every member of the herd to question these goals and not merely pursue them blindly.
Being human entails autonomy and thus a capacity for moral responsibility of our own choices. This is the basis of all human rights.
But if you merely pursue the goals of your herd without questioning and examining them -- like an automaton following the one in front of you -- you abdicate your moral responsibility. Though not ideal, this is still bearable for this is itself a moral choice -- even if a bad one -- and concerns only you.
However, what is morally abhorrent is denying others in your herd a chance of questioning and discussing its goals. In doing so you deny that autonomy for moral choice which makes us human. (Of course, some may point out that it will be an impossible situation because two members of the herd may decide on contradictory goals. But that difficulty can be handled by some agreed upon rule -- votes, for example. In that case everyone is still allowed to make their own choices even if their preferred outcome is not achieved. What is immoral is disallowing equal chance to anyone to discuss and influence the goals of their herd according to their own conscience.)
This is the moral argument for tolerance of questioning and discussion in a herd.
There is also an instrumental argument. The herds that allow the collective intelligence of the member to discuss and choose goals are more successful and resilient. Conversely, the herds whose self-definition is based on taboos -- we are a herd that does not discuss this or that -- will disintegrate sooner than later.
[*It holds true of all herds -- your nation, your religion, your organization, your sports team or whatever herd you feel part of.]