Mr. Dubois is a character in Starship Troopers

(the book), Baja. Essentially he's really Heinlein's voice in the book. Far as I can tell Heinlein is using Mr. Dubois to get his personal philosophy through. I thought it was an interesting read but I agree with you and partially agree with him. I agree that a child being spanked isn't a bad thing and can help but that does depend on the parent cause some parents won't know how to properly punish their kid and just be too aggressive (he sorta states that with a puppy being hit every hour, too much won't get the point across).
If you realize, he is basically making the assumption that Humans are born without any good in them and society is what keeps us in line(this is the opposite of a Romantic's view who believes they are born good but society corrupts). I don't agree with his view there either (nor do I really agree entirely with the Romantic's view

) cause we have some morals, in a sense, naturally in us. For example, we're a social being, we've evolved to know that working together is better than working alone (in terms of survival) so I have a feeling most are born with that sort of good, that they won't do serious wrong (they might have some moments where the group doesn't agree and seen as somewhat deviant, but for a social creature, it isn't going to last long so long as people don't like what s/he is doing). I think the problem more are the few bad apples that kinda cause a ripple-like corruption effect. In my opinion, society and humans aren't independent, one isn't wrong and the other the right that keeps things going, but linked (that should really seem obvious considering we invented the type of society we have). I do think that perhaps a few bad humans did corrupt society (and other humans around them) and that corruption in society will corrupt a few more so it's not like one exactly solely is the cause of corruption or a human acting in lesser than ideal ways, but both playing a part in them acting poor but also plays for making (in a way) an "ideal" human.
I hope that made sense

I'm a bit tired since I just woke up but ya. I agree that kids being punished through a physical punishment isn't such a big deal so long as it's done right (not too much, not too little, punishing and showing that what they are doing wrong by being angry about it). Beating a kid until you break their bones is wrong, but spanking them a few times on the butt isn't going to scar them for life >.> hell, Singapore uses corporal punishment (and they do so as bad as being whipped, I think Thursday is always the day they have whipping or canings or whatever) and, if you don't count the Vatican, they have the lowest crime rate in the world (if not, than one of the lowest). Where as we have the highest and our punishments are never really THAT bad specially for some crimes that are really horrible :|
However, just saying again, I don't agree entirely with what Heinlein was saying in that section but I do agree that corporal punishment isn't necessarily a bad or wrong way to punish someone and I agree that punishments should be cruel and unusual for the reasons he stated

I just really found this an interesting read cause it had thing I agree with and things I don't but it makes you think and that's something I enjoy.