You are right. It is not a true distilled water.FWIW I don't consider that waste (from AC or a dehumidifier) to be true distilled water, it is condensed on the outside of the radiator therefore that water washes over the aluminum rad plus the cooper piping. As well as the environmental contaminants stuck to the rad. It's quite the opposite and I consider it dirty water and wouldn't use it at all. The copper pipes and lead were just a reference pointing out the fact that we are eliminating them for a reason.
But, it is not dirty water any more than rain water is. Humans have been growing food using rain water or the water from nearby lakes, ponds or rivers for centuries and the plants survive and feed the people.
Even when pouring the purest water on the soil would pick up metals that are present so I don't know if it would be any different at that point than the water dripping off an air-conditioner or collecting in a dehumidifier.