As I see, I will be minority here. But I prefer to be optimistic in regard to this matter. I think that poker can be a good game for anyone. Nobody needs to play for money. Here in my city, many people, especially older people, play lots of other games gambling their money. People don't need poker to burn their money when they have it.
But instead of teaching Hold'em only for the mere act of teaching, maybe it is better for children and teenagers to learn how to evaluate if some game is a luck game or a game that demands skill. They should be able to calculate risks for anything in life, and act accordingly.
They don't need to play for money. Children can play poker for fun the same way they play chess, dominoes, checkers, or any other card game.
Of course there is a whole history of gambling associated with the game, but this is changing. With tournaments and with the spread of information, people are now playing the game not only to gamble, but as a recreational or even a professional activity.
If we were to completely ban poker because children can end up gambling, we would have to ban games like Uno as well, or even other games. Children can even bet the few bucks they have in any other thing. Instead, we should protect them from betting money, not from knowing a great game.
The problem is not poker itself. However, the teacher should be honest in regard to what he wants to achieve.