Why does censorship explain such sharp decline in comic industry?

David Hajdu's proposition (with some evidence) that censorship led to sharp decline of the comic industry in early 1950s is only one explanation. As David himself alludes to in his book and discussion, there are many other compelling reasons.

Comics were a source of expression and outlet for the immigrants. They were alternative forum for commentary on the society and body politic.

And here is an important data regarding immigration population. After very sharp increases in the immigrant population between 1900-1930, the numbers started declining in 1930s and 1940s with even more sharp decreases in the 50s and 60s.

So really the immigration population and hence the obvious readership for comics started declining in the 50s because of the aging of the old immigrants and the declining number of new immigrants. The decline in the comic industry is probably is better explained by the decline in natural readership.

And this does not ignore the prickly and prudish censorship of the 1950s but one has to concede that a society's tastes also change over time.