I'm not really sure what someone would expect an FO to do, while already on a trip. It isn't like the uniform store is super available by that point. Hopefully most everyone is professional enough to have pants that are at least within a couple shades of the correct one. I don't really know what you do with someone who can't make that happen, especially making what an FO here makes these days. That isn't a TMAAT question id have a great answer for, other than "I can't fix that" and "not my hill to die on". Yes, if they were bright yellow pants, I guess it would have to be said, but some type of dark pant that didn't look ridiculous walking next to me in the terminal? I dunno. This isn't the military.