Dave,
I'm confused as to why you feel our concerns about the wrestling is placing judgment on the girls. No one here has stated or implied that the girls are doing anything wrong. The concerns are more in regards to how the activity of wrestling may or may not have been originally introduced to the girls.
Considering the girls' pasts, it is not unreasonable to consider that their upbringing may have included activities which were not engaged in with a spirit of innocent playfulness by all parties involved. Again, the girls have not done anything wrong, either by wrestling in the first place, nor by challenging their aunt to wrestle. Their aunt did nothing wrong, either.
Many people here have an educational, personal, and/or vocational history of working with children who have been abused. While the specifics of abuse perpetrated upon these girls, and the level of such abuse, is unknown to us, the fact is these girls have been abused and neglected simply by the nature of their situation. To play therapists, and other folks familiar with social work, child development, and similar fields, wrestling brings up a possible yellow-flag. Identifying and reacting to a yellow flag doesn't mean you assume something inappropriate is happening, just that you recognize that there may or may not be an issue that may or may not need to be addressed in the future.
It is less a matter of being a sick, twisted person who only sees things from a sick, twisted perspective; it's more a matter of recognizing behaviors which may involve more than meets the eye. I hope that you can withhold your own judgment of those of us whose education and/or training influences our perspectives.