The politics of switching from sex based to gender based everything (starting with school bathrooms)

Considering that LGBTQ includes Lesbian, Gay, Bisexual, Transgender, and Queer (not sure what queen includes that the other gender don't). If we can agree that sex is a genetic term that includes Male and Female while gender is a sexual orientation that includes LGBTQ, than what is the core concern behind allowing different sexes or genders peeing in the same washroom? Is the concern sexual activity or physical violence in isolated places? 

Using sex to separate children may have separated boys and girls from forced interactions in vulnerable locations but why would that be important? Sex oriented washrooms don't prevent gay boys, lesbian girls, bi-sexual or queer kids from engaging in sexual activity in their sex oriented bathrooms but perhaps the solution worked for the majority. Gender oriented washrooms (which is being proposed) separate public washrooms by gender identity ideally address the sexual activity issue but are much more difficult to enforce and still fail bi-gendered children unless they are allowed in both washrooms. 

If the issue is physical violence than a separating children by vulnerability might be the solution so that vulnerable children have a special private washroom facility (this is what was being done in Catholic schools). The question becomes is sexual activity and violence really a problem at schools that needs to be or can be addressed by separating one group of children from another? Do we know the frequency or consequence sexual incidences or physical violence in schools? I believe these are real issues and any school system has a responsibility to care for and protected their children based on evidence for ensuring safe and nurturing environments. 

The issue it seams is different cultures (modern secular and traditional christian) have different views on what makes a safe and nurturing environment and in Canada's post christian society former givens are now up for debate. Not long ago we allowed parents to choose the school system based on their belief system and allow tax payers to choose which system to fund. We put a lot of power in the hands of parents to choose a system they believed in and we put power in the school administrators to protect children through architectural practices within their respective systems. 

As we move from sex based separation to gender based separation, is the solution better than its associated social impacts? I think the answer is we don't know yet. Unfortunately, scant reference to any of this research has been used during this short debate other than very general correlative data on who commits suicide or is bullied which we know is minority gendered children. How do gender based systems address switching or multi gender children? 

If rules become this complex and politically charged they become unenforceable meaning we are now in the beginning of experimenting with no rules. There are school cost savings of having a single public washroom but can this be done in a way that allows for children at all stages of their development to be adequately nurtured and protected? The ideological debate has certainly pushed us further than we have answers as of yet.