My comment to the guy would have been "yeah there are those that have the Beat 'em till they bleed! mentality!
Yep, he finally had to deal with a 'know it all'. My husband and I work in our family's business...I say that so you will know why my husband had to hold his tongue.
My husband goes to his job site today and while waiting on the unit, another man and my husband start chit chatting. Each of them talk about wives or not, kids or not and so on. The guy has married a woman with kids (he himself had two as well). Her son is 'hyper, batty, undisciplined, bad...' and so on. Yes, this is how this 'step' father personifies his stepson. YUCK! and YIKES! right.
So anyway, my dh goes on to say "Well, you know, our middle son is six and he struggled as well and we finally had him diagnosed with ADHD..." and as my husband is fixing to try and give this man some truly helpful advice, the guy calls him on it with "Oh, what Bull Sh**! Yeah, I guess it's fine if you need a scape goat but those kids (including his own step son here) just need vigorous discipline (OF COURSE, why didn't WE think of that). Or you could do what everyone else is doing and give their bad behavior a title and drug 'em up so they walk around like zombies!" My husband sat there furious and all he could do was say "I guess we agree to disagree." The guy wanted to debate it, I believe, but my wonderfully smart dh decided to walk away from the situation. Ugh!!! He called me as soon as the job was over and I said "Oh how I would've loved to have gone head to head with that guy!" Seriously!