I see that it's a bad choice for an example, as his stylistic choices were just on point for the intended formality. However, I wasn't trying to make a point about Vox's outfit, and if he cared or not doesn't matters for the topic being discussed, which is the cloth's formality.
So, if I got you opinion straight, fresco can be used for a casual coat, depending on the color and depending on how the coat is designed. Agreed, but how about those more suit-ish colors and designs? For example, navy blue sb with flapped pockets and notch lapels.
I know whether Vox care's or not is irrelevant - the statement was supposed to be flippant, dry, and mildly humorous.
I'm sure that there are stylistic choices (color, pockets, lapels) which lend themselves more towards suiting than Jacketing, but I would imagine those get pulled into a larger conversation about fabric formalities. However, from what I know the general consesnus is that fresco blurs the line even in this case. For example, see the definition of the blazer suit, which is a navy fresco suit where the jacket is styled suitably casually to be able to wear as a separate.