>>5293070MS are glossy in almost every gundam series, especially modern ones. Besides military vehicles being painted in flat colors, modelers often use flat coats on smaller scale models due to the effect of colors appearance flattening over a distance. It helps give a sense of scale compared to leaving it glossy.
Of course, painting it domething like this would be the most accurate to its in show appearance, but I have no idea how to go about positioning the highlights.