Its a little tricky too, as children generally don't have suitable investment accounts that can hold publicly traded shares. I'm doubtful they even legally can open those accounts.
So what are they going to do, issue a gazillion single paper share certificates? What a shitshow that would be, the fees and shipping alone around dealing with that for a single share would be nuts, not to mention the hassle of redeeming them, and the untold numbers that would be misplaced or destroyed. And I'm still not sure children can own them, or sign the agreements required to get them.
What else could the do? Create beneficial trusts for every child? Whose going to administer that? and again the fees and management expenses around it would be nuts all for a $150 space-x share?
It might be reasonable for him to set a bunch aside, and as children reach adulthood, let them claim them at that point.
If the idea is that the kid can't sell it or whatever until they're an adult anyway, its probably fine. It'll be income maybe when they receive it, so that could work out badly for some kids though, if they have to sell it to cover the taxes on it, because they don't have a job yet. Especially if its appreciated to a couple thousand or something. (How are splits etc handled, do they get one or more? Or worse... reverse splits on a single share?)