Welcome
@Hkim0019
Thank you for your story and it sounds like an unfortunate encounter. Im sorry your parents felt unwelcome.
Emergency exit seats (EES) come with certain requirements. Basically the EES passengers need to be able to understand and carry out the instructions of a flight attendant. The person that determines whether the EES passenger is able to carry out those instructions is the flight attendant.
Unfortunately it matters little what your folks think. As soon as a EES passenger asks the flight attendant to repeat the question, it will give the FA cause to think that maybe the EES passenger is not up to the task, and the FA's opinion is non negotiable. Imagine a chaotic emergency situation with multiple distractions - crying baby being one.
Best is to put a complaint in but stick to the facts rather than the assumptions of perceptions.
And stick around and join the crowd here for some fun stuff.