HIIT is very demanding on the body, so I wouldnt do it on an empty stomache like that personally...just do regular cardio in the morning if thats your goal. It takes a lot of energy, so I dont think you will get much out of it on an empty stomache. I think HIIT is best shorter and more intense, so that you can really sprint during the intervals. This way, you can help prevent muscle loss as you are burning calories.
Also, it depends on your goal. Shorter HIIT will only be burning calories from fat, where as longer cardio sessions will burn more calories, but from other sources. That is why shorter HIIT sessions are ideal for trying to maintain muscle mass while cutting.