The school attempted to make allownces for the kid to use the single occupancy facilities.
IIRC, most public mens rooms have at least one sit down toliet with a stall.
If the kid has a problem using the urinals, he has other options and at this point, I hesitate to feed into the transgender role. The kid is 6. Exploration, even of oppisette gender roles is normal. Gender determination and sexual identity won't be all that relvent or clear for some time. Hindsight 20/20, many LBGT people knew when they were kids that they were diffrent, but didn't understand the diffrences at the time.
Parents need to stop pushing that kid and just let him develope as he will within the current gender culture in this society. If he chooses to identify diffrently, he can and will in his own time.
Finally, I distinctly remember then when I was that age, when I had to go, I had to go, and getting to a toliet was a hell of a lot more important then gender. I'm pretty sure, when push comes to shove, the kid is going to find a facility to use or wet his pants. If the parents REALLY want their presious baby to feel comfortable at school, they wouldn't screw him up so crazy that he'll end up peeing himself trying to figure out where to go and spend the rest of his school days with his peers tormenting him for it (along with everything else)