Ok so I'm gonna do this post even if I am a little bit scared and I will probably regret it but I'll try not to.
I am the first person to be happy about Shiro's sexuality revelation like it's so much important nowdays to have a queer main character - a hero - in a show supposed to be for kid (WHICH KIDS GUYS I AM 20++ AND I FUCKING CRY IN EVERY EPISODE) and I really wanna find out about the story with Adam, what happened, how, why, which were the issues and etcetera.
BUT 🤷♂️🤷♂️ I'm not gonna lie, I will probably still shipping Shallura (*coff* Shallotor *coff*) and headcanon Shiro as pan till the end of my fucking life.
I'm making this post cuz.... well it never happened to me in the first place but I know of fandom and people who were treated not so nice just cause they had het ships with a queer character.
So the fact that Shiro was with Adam doesn't mean that you cannot headcanon Shiro as bi or pan. Gay? It's ok. Bi? It's ok. Pan? It's ok.
I mean just... not be afraid to make as much headcanons as you want and to ships whatever you like the most. You are not wrong and you don't have to be afraid and if someone ever tells you otherwise... well they are the ones wrong.