I love how we call everything in the FOM “guidance” here, then get completely wrapped around the axle over the slightest deviation from the most trivial language in the book.

Out of a group of 20 captains, you’d be lucky to find one who is actually going to say something to an FO about a North Face jacket. And by the time a new hire finds that one captain, they’ll already be on their way to upgrade training the next week. Unless an FO is doing something unsafe, illegal, or likely to land one or both of us in trouble, they’re not going to hear from me about it. This issue doesn’t rise to any of those levels at all.

Personally, I prefer that the pilot performing the walkaround be as comfortably-dressed as possible so that they can focus on doing a good preflight. Nobody cares what type of jacket a pilot is wearing when they have an ugly neon safety vest over it anyway.