You were ticked off that someone made an assumption about your situation, why would you do the same? Are you rationalizing?
I can tell you that your assumption is flawed. My children received my time and attention all day long because I INVOLVED them in all my activities. And the benefit in that is that I directed their activities to teach them the values and behaviors I wanted them to learn through targeted play.
We PLAYED all day - our vacuum cleaner was a "goat" who gobbled up the bits of paper and stuff on the carpet, grocery shopping was a game of I SPY and looking for familiar faces on the labels of the products on the shelves. We "practiced" good behavior and bad - before going into a store, we would "get the Beggings out" by yelling at the top of our voices (me too) YOU NEVER LET ME...I WANT CANDY...HOW COME WE NEVER GET ANYTHING???? The kids thought it was a hoot, and if by chance one of them got a little whiny in the store, I'd say, "Whoops! I thought we got rid of all those "Beggings" when we were in the car....quick--put it in my purse! And I'd open my purse up to her mouth so she could (giggling) get the "Begging" out of her.
My kids were having fun, but they were also learning the lessons I wanted them to learn. If your child's "friends" at school are being raised with values similar to yours, perhaps it will work out fine. If not, you'll know that too.