Some of the comments are missing the point that this article isn't about the lap dancers, or whether that is an acceptible profession. It's about yahoo's decision and whether it was appropriate for the convention.
If the hackers had been brought up on stage and a priest came out to give them communion, that would have been inappropriate, even though being a priest is a fine career and many people take communion from priests. It just isn't appropriate for the convention.
Not everyone wants to get a lap dance, whether or not they think lap dancing is an ok profession. (And not liking lap dances doesn't mean one doesn't like s3x, as one poster implied.) Suppose one of the hackers selected were married, or in a monogamous relationship? He could have felt uncomfortable. And in general a convention organizer should not make the attendees feel uncomfortable.
By all means go out and enjoy s3x, or have a lap dance... but not as an official part of a convention.