Being an Englishman I firstly don't know who Joe Biden is - I assume some sort of politician. Secondly why does it matter if he served in the military - is this a plus or a minus point for a politician in the USA ?
I would have thought his greatest attribute would be his honesty and ability, something sadly lacking in politicians of any political colour.
Or perhaps he doesn't have any, in which case there is your answer !
Kind regards Peter