Just jumping in here.
I had never thought about the hypothetical situation of an entire population of clones, but here is my take on it.
Despite the fact that they are clones they are still not equivalent.
At the risk of misusing the term there is still "variation."
It wouldn't be genetic variation (at first).
None of the individuals can be in the same place at the same time so
there will be at least slight differences in their experience.
Then, of course, there will be plenty of room for mutation as time progresses.
Since, most likely, some individuals will die before they reproduce and there is
still mutation going on, then you still have a NS situation,
especially if some individuals reproduce after a mutation.
I know this has nothing to do with this argument, but if there are some misconceptions here, please let me have it...