Well look at the birth rate in most Muslim countries, got to start them off as young as possible for that kind of birth rate! Although you would think that they would have the decency to wait until they were at least nine like the prophet did.
Seriously though, it used to be common in the US to marry off girls as young as 12 or 13 years old so if this was just a kind of engagement ceremony and they wait at least until she is past puberty I don’t really see a problem with this. Probably the only way that the groom can see what his wife is going to look like before he marries her because after she does hit puberty she has got to wear a veil and since he’s not a relative he couldn’t see her until after they got married.
Oh!! Well.....that makes it OK then.
“got to start them off as young as possible for that kind of birth rate!”
Getting girls that young pregnant would probably kill most of them off during labor, so it would hardly help the overall population rate.