I guess because there are so few brothers in the congregations, sisters start writing to brothers that are in prison. In prison, these ne'er do wells have no bills, no job to commute to, 3 meals, a bed, free medical insurance and loads of time to read the Bible and the WTS publications. Oh my, kinda like Bethel. I guess they seem so spiritual that sisters just fall for these men --- hook line and sinker.
I just cannot imagine marrying a man in prison!! Especially ones that will never get paroled. But "never" is not in the JW language when it comes to "worldly" structures in place. I would have to think that behind closed doors even JWs think that sisters who marry jailbirds are cuckoo themselves. They probably say the PC things to the sister, but amongst themselves, the elders have to just roll their eyes.
And I guess its not such a bad arrangement, afterall, Armageddon is just around the corner and the prison walls will fall down.