I wasn't there and don't know what you ate, but if you just did one big episode of vomit, it sounds more like something you ate vs. a virus. Being a kid, relying on your parents is what you should have done. If they were concerned, I am sure that they would have notified the medical staff. I don't think the stateroom host would ever be in charge of notifying medical. I suppose if they had to change soiled sheets, they would have possibly said something.
For me personally, if I threw up that much, I would have kept myself locked up until I was sure it past (like 24 hours after event with no other symptoms). I was a throw up queen as a child and would vomit all night long whenever I ate chocolate or was nervous about anything. Once in a while, my mom would take me to the doctor for it, but he always said there was nothing to do about it and never prescribed anything.
I'm glad you are okay. I am sure you parents know you better than anyone on this board and made the right decision for you at the time. The shorter answer to your question is No, the stateroom host should not have quarantined you. That is not their job.