My opinion is that if it works for you, it works.
I can think of a number of different shapes of bullhorn handlebars, some would work better than others, either swiveled so they're upside down or fully removed and rotated 180. Might have trouble with some configurations if you have to steer too tightly though.
But what about this: bullhorns are basically road bike bars that have been flipped and chopped. What if you just used those without chopping them? That would help get you higher up.