What is a poorly thought out risk? I opened a box that told me there was a Serial Killer potentially, and which gave me x-shot investigate for SK. I could have read Numbers' extremely rapid claim of the 2nd kill as an attempt to get people to believe he was a vigilante and not consider the SK angle, but if you read my comments yesterday you'll see me raise the possibility of SK several times.
I think it would have been a poor play for me to reveal yesterday that my "I'll Never Work for Cerberus" box had made me an x-shot SK cop, which would have pretty heavily implicated Numbers before I could actually investigate him and (assuming nothing messed with my investigative result) would have resulted in us probably killing someone who appears to have been honest with us all the way through the game.
It's still possible that Numbers is scum, but nobody has actually made a case for that. The mere possibility that he could be isn't a case. Everyone in the game could be scum.