A LL is not required to disclose issues unrealted to the property. Karen gets a little carried away, where would you draw the line, the next block down, 2 miles away......really now....
Just because someone got nailed as a SO is no reason to go off the edge. There is a difference between some 19 year old guy with his 17 year old girl friend getting in trouble and some 59 year old perv.
At 30, I'd still wonder about the circumstances, some at 17 look, act and carry on (and lie) as older women who may work the street or a bar parking lot. Just saying I'd want to know the circumstances before getting excited about it. If he snatched her off the street and violated her, he would have gotten more than 5 years, sounds like there was more to it. And no, I'm not some Akin type suggesting it was her fault.
I doubt you'll have rental trouble, such is getting common in some lower end areas.