They don't understand that the great majority of people in the country would be upset to see either behavior. Letting kids perform in ways reminiscent of sexualized adult performances is not a good idea, not good parenting, and one would think that even Portland liberals would realize that whatever one thinks of LGBTQ issues, it is best to keep children out of the mix.
What you say below is true, but that view is obsolete in liberal circles. Here on the leading edge of cultural liberalism, these events are considered family friendly. It is the new civic engagement venue. Parents take their kids to gay pride events.