Zero, the line is at zero feathers.
“No feathers in the hair” is bad enough, but…no feathers in the hat? That’s a like…codified sartorial thing…like a pocket square on your suit…it fits within an idiom that is so clearly and utterly orthogonal to anything ~tribal or ~indigenous–or even ~hippie or ~boho–that I can’t find any rationale for this shit even within OP’s austere and rigid framework. Andrew Ti, explain yourself sir
…did someone misunderstand something here or does it actually say what I think it does
Like, think there might be some misunderstanding here. But if there isn’t then s/he just forbade wearing a feather in one’s hat which is part of traditional dress for one of my ancestral cultures. Which is european in origin.