Zahard is the literal, de facto, knighted KING of the tower. That much is inarguable.
If a FH defies Zahard, they are defying a king, and thus are turning on their boss. They might not see his as such (or a false king, a la Arlen), but he's still the king nonetheless, while they aren't.
He's also the strongest among them.
So.... yes and no.
Zahard is the official king .
In fact Gustang called him a self proclaimed king .
Do we have any idea how much off them consider himself a king ? In fact what does a king even mean for a irregular ?
Who made Zahard a king ? Would have zahard been king if it wasn't for those irregular accepting it ? Doesn't that mean that if they don't aknowledge him he isn't a king ?
Zahard power is shaky and it doesn't matter if people recognize him as king , what matter is if the FH recognize him as king because they are 10 irregular , so basically Zahard legitimacy stand on whether those irregulars accept him or not .
If they don't , what will happen ? The competition for the next king .
That is why despite Zahard cursing native one tribe because he felt a treath from them according to you , killing baby baam he couldn't move that much to kill Baam .
Because like this chapter show Zahard , " the king " couldn't move because off his comrade other irregular .