I'm kind of skeptical that they even tried to reach out to diverse people. For example, Keavy McMinn indicated on twitter they never asked her. She's a very well known and liked speaker in the Ruby community and lives relatively close by. If you largely reach out to white guys, of course that's who you'll end up with.
I'm not sure I like this argument. Because one woman (who from your comment I presume everyone should know about - I don't know her) said they were never approached, this means the organisers intentionally selected (using your words) 'non-diverse' people?
Their argument was that there were only white guys available from the list of popular ruby presenters. I'm saying they may not have tried very hard to reach out if they didn't even ask a closeby popular presenter (yet they asked a ton of white guys from the US). There were others that also weren't approached - I mentioned Keavy specifically because she spoke about it publicly.
