If your child realizes you're uncomfortable talking about their giftedness, they will take from that that it's something to hide and be ashamed of. I spent years trying to hide the fact that I was gifted in large part because I picked up on the fact that adults constantly sidestepped the topic of my intelligence. So I say be confident, be honest, and be open. Sure, don't start the conversation if you think it might lead to unpleasantness, but when somebody else brings up the topic, why should you hide the fact that your child is gifted and you're doing the right thing for them? I've read that Hoagies article, and the other three rules are great, but I think Rule #1 is absolutely dead wrong.
I think it's hard to balance not seeming embarrassed about giftedness with not seeming to be bragging. I think Rule #1 is really about not looking for the approval or advice of others, and that I agree with. One of the reasons for forums like this one are because here we can share BTDT stories with and get advice from people who get it. It's hard to do that in real life sometimes.
But I also agree that giftedness should not be treated like it's a dirty little secret. My mom acted that way in her Christmas letter to friends to explain why DS8 was being homeschooled, and her friends all thought my DS8 was a troublemaker who got kicked out of school. SO not true! And that could cause real problems for DS8 and I socially if I were making the same mistake she made.
I decided that I'd rather be honest (but brief and matter-of-fact) and risk having people think I'm bragging than to have them think he's a juvenile deliquent!
I do think there's a middle ground.