My grandson and his parents-should I just butt out?

My grandson will be 2 in mid-July. My son and daughter-in-law do not live close to us so we see them 3-4 times a year. This past week they came home for an important family gathering and I am disturbed at my grandsons progress or lack of as far as communication. My son and his wife are WONDERFUL parents, but I am wondering if they are too doting. My grandson points and they jump-- he throws temper tantrums when he doesn't get his own way and they do nothing about it. He speaks very little although I know he can as when it is just him and I-he will talk up a storm. My husband and I babysat one night while they went out with some friends and it took me a while, but we finally had him running around-playing and rolling around outside. He was having a ball. He got dirty like I have never seen him (which is really not allowed by my DIL at all) and went to bed without issue and slept all night long. They picked him up in the morning and he was winey and moody all over again. They live in a very warm area, where it gets pretty miserable outside--so they stay in the house alot. They watch tv quite a bit and since they work alot (she a restaurant manager and he owns his own consturction company), he is at the sitters alot of the time. He is as smart as a whip--I do not believe for one minute he isn't able to do all the things a 2 year old should do, he just doesnt' when his parents are around and they don't make him. They have just entered him into a new daycare/nursery school that I think will benefit him greatly--playing with other kids and having to speak etc. I wish he lived closer so he could spend more time with us (we live on a farm and he LOVES the animals) but that is not possible. The stories I hear from my DIL about her upbringing, her parents were very, very strict, bordering on cruel (opne side of the story I know) my son was disciplined and to be honest once he got past about 7-8 years, I hardly ever had to discipline him, he had a good solid basis of right and wrong. They are both loving parents and I know they believe they are doing the right thing and only want whats best but sometimes I think they are too laid back with him. So do I keep my mouth shut or do I say something to my son/DIL? The not discipling is the part that really concerns me. They have to have a good solid base or they get out of hand as they get older.