Some further ideas to help you in your analysis:
I think there were two ideas being contrasted: 1) That the Soviet musicologists were censoring historical music; and 2) that they were trying to influence the current and future composition of music. Some key ideas I found in each paragraph:
Paragraph 1 - a discussion of the rehabilitation of pre-1917 music. To understand this paragraph, I think you would need to think about the Russian revolution, which happened in 1917. So, the author is describing a revision of the history of Russian music pre-1917, so that it reflected Socialist ideals
Paragraph 2 - By the 1930s, this new Soviet music was described as National and popular, and we're told that Soviet states were using art as an educational tool ---in the context of Soviet ideals, this would mean using art as a tool to control the people. AS A CONSEQUENCE (the author uses the word consequently), this became the model for the Soviet composers
Paragraph 3 - Defines the job of the musicologists to 1) revise the composers of the past; and 2) present models for future composers
Paragraph 4 - talks more about contextualization of past composers --- to me, this seemed like the context was Soviet ideals, and the contextualization really meant censorship.
So, paragraph 1 discusses censoring older music, paragraph 2 discusses providing a model for current and future composers, then these concepts become more concrete in the 3rd and 4th paragraph.