As i said in your other homophobic thread, no body forced any of theses grown men to pose for these magazines.
regarding the magazines in the 1950s, many young bodybuilders were shocked to find their picture on the covers of these blue magazines. the photos were taken by a professional photographer, but once you sign the model release, the photographer can sell them to anyone he chooses.
this was a big controversy in the 1950s, and they threatened to ban any athlete that ended up on such mags (this is probably why Larry Scott left the AAU and joined the IFBB). but it was simply that the 1950s became more conservative. look at all the early Strength and Health from the 1930s and 1940s. more often than not, the photos on the cover were nudes with the posing suit drawn in.
Harry Pascal, who was the executive editor of Strength and Health for many years, never missed a chance to bash gays (among others). He was the one screaming the loudest on purging gays from bodybuilding. Yet his staff photographer was Lon Hanagan, who is now considered one of the best of the gay erotic photographers of the 1900s (google Lon of New York). Lon was the photographer for most of the photographs with the posing suit drawn in on the negative that were used in Strength and Health.