You can believe what you like. The imagery is based on this latest evolution of the rainbow LGBTQ++++ flag: https://www.them.us/story/progress-pride-flag-intersex-inclusive-makeover .
The blue and pink triangles actually come from the trans flag https://en.wikipedia.org/wiki/Transgender_flag .
It doesn't really serve any purpose to put pedo symbols in this context. If you run a pizza parlor or donut shop or charitable organization that serves as a front for some nasty pedo stuff that happens in the basement, yes, you might put some pedo symbols in the window because you're looking for your birds of a feather to join you.
This is a different type of evil. By putting one of these stickers in every teacher's mailbox, they are drawing battle lines. They are saying either support the LGBTQ++++ agenda openly, or make yourself out to be a non-inclusive bigot, so take your pick. I saw several Christian teachers post the sticker, but a few of us stood our ground and did not. This post displays my counter-offensive. They can't say I'm not being inclusive now. In fact, mine is arguably more inclusive.