Parents and grandchildren

My brother and sister in law are expecting their first child in a few months. They live in a different state - a six hour flight away from my parents.

My brother and sister in law told my parents that my sister in law’s parents will stay with them for six weeks after the delivery and then my parents can visit for two weeks.

My parents are genuinely hurt that my brother and sister in law basically won’t let them see their grandchild until after six weeks. Before this conversation, they were planning to be there on the delivery date as they have done for every other grandchild.

Do you think this is right? What should my parents do?