Cause well if someone does not have kids and adopts a greyhound and then later has a baby,the dog is not taken away! So you do make a good point,but one I have no answer for.
I have to say that like every where, there are folks in rescue who are just not all that great with their people skills.
And sometimes those people have seen a lot, dealt with a lot and this makes them less then hospitable when certain situations arise.
Do not let this get you down.
Personally as a rescuer I would have jumped at the chance to offer you more information. I encourage anyone to research a breed and dog care before obtaining a dog.
She should have respected (and viewed it as a good sign) that you were willing to wait and admitted you were not ready for adoption until your child was 4 or older.
Their policy is probably for the child's protection. I'm not defending them,though. Maybe try a greyhound mix? My neighbor has a rescued greyhound, and she is very low key and sweet, even good with the cat. So maybe call back when your child is 4?