That sounds seriously horrible.
I'm really hoping that this meant to be a sweet pudding and not a savoury salad course.
1. It was seriously horrible. MrsTasty tried it, then whispered in my ear, "If this is what the Hapsburgs were serving, no wonder someone shot Ferdinand!"
2. Yes, that would be a dessert. There are a lot of "Jello mixed with whipped cream/ice cream/sherbet" desserts, usually with fruit in them.
There are, unfortunately IMO, just as many mixed with mayo or cottage cheese, that may have fruit mixed in, or veg mixed in, or both. When I was a kid, it was always a good idea to be mindful when others were trying the green jello, just to gauge the reaction. Smiles, probably has ice cream and fruit in it; frowns, probably has onion and celery in it; look of utter confusion, probably has a bit of both.