Going to the children's play museum is making my son resource guard

Idk how else to describe this.

We have a children's discovery museum with loads of toys and fun stuff. My 18mo LOVES all the stuff in there. Like his favorite place on the planet he would go every day if I let him.

But the other kids in there are big, out of control, and mean to him : (

They take stuff out of his hand or push him away from his activity all the time. When he first started going there he was always going up to other kids trying to play and handing them stuff. Now he like guards anything he has, and runs away from other kids and cries when they get too close because he thinks they will take his thing.

It's not a wrong assumption and it breaks my heart

Feel like we can't go anymore. I am lost on what I'm supposed to do. I try to protect him but I can't parent 100 other kids at once and they are quick. It's not all bad obviously but enough just go around being mean that my poor son can't really enjoy the activities consistently and I feel like it's affecting his perception of other people.

We went today and I had kids prying balls out of his hand and basically sitting on him to access what he was playing with. My final straw was he was "flying" a plane, sitting in the chair pushing buttons and steering and loving it, and some big kid literally sits on the chair he's currently in and blocks his view and ability to touch the controls. He cried and starts hitting the boy on the back because he's being sat on. We had to leave he was so upset. And I don't want him hitting obviously but when a 7 year old is sitting on him????

Just not sure what else to do besides stop going there. I wish I had some parent friends with kids he could play with regularly instead of exposing him to The Jungle constantly. Where it's a more controlled environment he can have POSITIVE interactions with a small group of consistent friends he can enjoy and maybe won't take his things a dozen times in 10 minutes

Anyone else dealt with this? Why is everything so hard I never thought I'd be a mom who is trying to manage his interactions too much. But this feels extreme to me and like it's affecting his mental health. Am I totally off base here?