nephew spit up on me

I usually try to keep my distance from my nephew, he’s 9 months old but he is constantly drooling and spitting. Yesterday my brother-in- law sat him next to me on the couch and he slowly starts crawling towards me. Obviously I would feel like an asshole but I wanted tell him to please grab him so he doesn’t crawl on me. Well what do you know the parents aren’t paying attention and the baby comes and spits a huge warm glob of saliva on my leg which soaks thru my pants. I immediately look down in disgust and the dad goes “Oh, sorry.” In way that clearly sounded like he didn’t give a shit. The mom bursts out in laughter. I literally was so grossed out and honestly pissed. I get the baby can’t control himself but his parents can, and the fact they just laughed at me being disgusted was disrespectful. I went and changed my pants and even his sister who has her own kid asked me if I was okay and agreed that it wasn’t cool that they just laughed at me. It’s no surprise as this kid is always messing with our stuff and his parents have no regard for it. He chews our tv cords, licks the tv, chews on our cats toys, and his parents never stop him. I was so overstimulated I ended up leaving right after it happened. Why is it so funny for parents when their kid does something gross to someone else. Especially someone who’s made it known they get grossed out easily…