Hard to say without knowing your DS or parenting style.
My dd never behaved like that. Though whether that was down to my parenting or luck who knows?
I did have a friend with a very boisterous boy and her parenting of him IMO was awful. He wold misbehave, she would threaten him with a punishment, he'd do it again and she wouldn't carry out the punishment. However, I bit my lip and never said anything even though he used to hit dd. we did keep our distance for a while because of it, I felt I had to protect dd.
It does sound from your description as though your DS may be somewhat overindulged and you may indeed be making a rod for your own back but that is your business and not hers. She doesn't sound like a friend worth having if she would try to force her opinion on you and diminish your confidence.
I have a lively and clever 3 year old. He is boisterous and resorts to hitting when there are problems usually related to toys. He went through a biting stage but this has (thankfully) stopped. He is an only child and when I am in the company of other adults it is someimes stressful as he constantly seeks my attention. Is this normal? He is a loving and very cuddly child. I am struggling to deal with a particular 'friend' who is openly critical of my parenting style. I am appalled that she seemingly things it is ok to be so openly critical. She has told me my child has 'behaviour issues' which will develop into a serious problems. I work as a teacher and do not think this is true but it has impacted on my confidence and ended the friendship, which does not bother me as her attitude has not been a one off. Any comments ideas would be appreciated.