I got food poisoning when at an American university and I used the university hospital. They followed up with me to ask me whether I ate out anywhere. Next thing you know they've gone and done an inspection on the place and it's closed for a couple of days. Seems a bit high risk.
Tbh I think I got sick off my own food but I was doing the thing where I just honestly gave them all the info. I never really expected anything to come of it.
No, restaurant workers will not mess with your food in that way. No matter what they think of you as a client. Ask people you know who have experience in that sector and they will tell you that such things are absolutely taboo. Anybody who did anything like that even once - or even suggests it - would be instantly fired and blacklisted in the community.
If the waiters or chefs hate your guts, at most they will swear in the kitchen.
It might not be a great idea to frequent the place if that's your chosen form of social protest.