I don't think it would have hurt them to err on the side of caution on this one. It's certainly possible that their background check simply was unable to see this information, but given the pattern Uber seems to be building for themselves here, it would be really hard for me to believe their explanation of what happened anyways.
Throw the other problems away: this is the actual problem at Uber. The fatal flaw Uber continues to make is that they fail to build trust, which brings their activities into question every time something like this happens. At this rate, it's just going to keep getting worse.
I actually can't believe the board hasn't taken any action here. I've never in my life seen a startup more in need of a board intervention.