slimboyfat:
More to the point it seems to be entirely in character.
Fraternal groups were quite popular at the time, and it if were him (which has not been established), it would be entirely unremarkable.
It is still not remotely clear why this potential 'discovery' merited multiple 'wows' and other 'excitement' in the initial post and some of the subsequent responses, since early membership of some group does not indicate any allegiance to or affiliation with that group later.