Looks like we'll get a chance to test their hypothesis pretty soon.
For the record, Father A. has spent much of the past year immersed in minutes of the United Lutheran Synod of New York covering 1929-1935. And he can say, categorically, that these were not good years for churches. They were terrible years. A missions committee that had been planting two or more successful new congregations every year ground to a halt. Pastors lost their parishes, parishes lost their buildings. Nobody got paid, nothing got built. Contrary to the myth, worship attendance wasn't especially good.
The AP article linked above gives a foretaste of the feast to come. It reads about the way a similar story would have read in 1930. By 1931, the stories were worse, and in 1932, nobody had enough ink to waste on newspaper stories.