MIL doesn’t respect our sons schedule

My MIL keeps asking to keep our son up... not take his nap or stay up way past his bed time. She gets super upset and tries everything, even taking him out of my arms when he was a baby and blocking me from grabbing him saying “oh he just needs something to eat or let me try to play with him.” She has done this for countless birthday parties (adult birthday parties) or Xmas dinner... it has been going on since he was a baby. He is turning 3 next month and it’s still going on. I thought maybe because he is the only grandchild on my husbands side of the family... but no.

Her 60th birthday is in a month and yesterday she got super upset on the phone telling my husband that she planned a brunch at a fancy restaurant and really wants our son to stay there and be at the lunch and all. We’ve been to the restaurant and it’s a fancy not kid-friendly restaurant. My husband of course says we will try but can’t guarantee anything, thats right before his nap. We are so thankful he takes a nap still. I told my mom and she feels most people would think the opposite like it wouldn’t be appropriate to bring him. I just hate the tension that builds up and feel it’s really unfair of her to get so upset. Our son has been having meltdowns before at parties because super overtired and she wants to still keep him up... I’ve had to just leave with him regardless how she is reacting cuz he becomes a mess. Now that it’s her birthday... I’m going to feel awful leaving if he becomes out of control.

I would like to add that he gets out of control and of course we don’t mind at all trying to keep him up but its when the situation gets really uncomfortable (he has been kept up 2 hrs after his nap or bed time and a mess) she still wants to keep him up, it’s really bizarre to me.

What is everyone else’s opinion? What would you do?

Thank you for your advice and opinions!