On ones own, there is no reason not to order food in any order you like, but at a business dinner, it is odd at best to eat courses out of order. There is an entire set of etiquette rules around dining out, from which utensil to use, which direction to spoon soup, etc. Among those are timing ones dining to finish around the same time as others at the table. It's not as simple as eat what you want, how you want, when you want. It is definitely rude to call the person out for a mistake, but that doesn't make ignoring the etiquette rule polite.
I don't think there is a rule saying you have to order course appropriate food, but I can't decide if it's because that's obvious to most people or because you really can order from any section of the menu for any course.
I'd vote it's not technically rude, but a really bad idea and distinctly odd.