I would have done it just slightly different -- picked the child up and held her in silence through the tantrum, even still sitting on the ground. That way, she can feel you there (in case it were a real melt-down -- say from fever or overstimulation, not something calculated), not get bruised, keep out of horse urine, and show other parents that you're not quite that cold. You were right to be absolutely boring and unimpressed. Two is probably a little young to understand "extreme waste of time."