Just like some Golfers or members of an amateur dramatic society may have the same access.
The fact that your grandfather was a freemason,had nothing to do with his "disappearance"
Freemasonry is a charitable fraternity,its members are ordinary men,it is not some sort of underground organisation that allows its members to hide from their families.
You are confusing Freemasonry with the "Odessa File"
I am a Freemason
http://www.ugle.org.uk/
why would you assume that was the reason he left? maybe he just abandoned the family - it happens - or he left to find better work opportunities and just never went back - he could have been sending money home
What does Freemasonry have to do with any of this?
My great-grandfather was a Freemason from 1920 up until 1926, when he "disappeared." However, I found a census record from the 1940's where it says a man by the same name, birthplace and immigration status is living. Is it likely he left the family to play the stock market before it crashed?