If it feels good, do it.
Jackets: Button rule questioned. - Page 3
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Maybe it was an accident. As if, when nonchalantly leaning onto something, the top button became askew, and he decided that it was better to appear in poor taste than to appear clumsy.
(+1 on this not being a good look, by the way.)
Maybe this nice elderly gentleman buttoned the top button and then realized the tip of his tie stuck out underneath