1) I am not sure that the notion social reductionism is defined as in your post. But let's assume it for the sake of the argument.
Then social reductionism is wrong.
A philosopher of science only needs to apply the historical method: Changes in science like the invention of Quantum Theory or the Special Theory of Relativity in the begining of the beginning of the 20th century cannot be explained in terms or approaches from sociology or politics.
Both theories do not bear any relation to politics.
Of course Quantum Mechanics has been invented in a stimulating academic context. Here sociology comes into play, but not as a main actor. On the other hand, the Special Theory of Relativity has been invented by Einstein single-handedly.
The driving force for both theories was the need to explain certain physical experiments and observations which could not be explained by existing theories.
A good reference explaining change in science is Kuhn, Thomas: The Structure of Scientific Revolutions. 1962
2) Concerning epistemic relativism see http://philpapers.org/browse/epistemic-relativism and the links within. The issue is assessed controversially.
At least concerning science, I emphasize the importance of intersubjective consense of the experts about the interpretation of the relevant experiments and observations.