Pregnancy differs between women as does HG. Some manage alright on strong medication...I managed, I spent most of the day in bed, taking my pills, and fighting the urge to throw up. I would crawl out of bed twice a day to do the school run. I had no choice.
I was lucky that my medication worked as well as it did though I still felt hideous most of the time.
Some people have it much worse and are tied to their beds vomiting 24/7. We have NO IDEA where Kate is on this scale. We're just speculating. There's no point.
To suggest though that a 10 minute appearance means she is making it all up, is just stupid though. She will have access to the best drugs, being in her situation, and injected ones work better than oral ones, and she may also have facilities to be rehydrated at home, too - we just have no idea.
If every woman suffering with HG was given the best meds and treatment available, we would all cope better too I imagine...but sadly that will never happen as it's intensive treatment and quite costly AFAIK. Even the 'good' drugs are held out on for weeks because they cost a fortune to prescribe...you only get them if you are really poorly. The rest of us cope as best we can.
Some people don't even want to take meds for it.
We really cannot assume anything about her condition from this appearance.