Although, stripping out the colour the hats themselves tend to seem in line with the style of hats worn by commercial pilots still and of the sort that you can buy yourself. Maybe slightly larger heightwise at the top but still broadly similar.
If formal uniforms are grey, then the hats need to be as well. Yeah, you can get a slightly Soviet vibe off it all but really that's the downside of making assumptions from a single behind the scenes image. There's absolutely no context to it.
Like the ridiculously small minded at times criticism online (and here a bit if I recall) of the image of Quinto suspended on a soundstage which will resemble the final shot or it's place in the sequence in no way as it was shown in the still.
Gotta have the context in the film.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist