All men of a certain age were required to complete draft registration cards. It doesn't mean they were actually drafted or engaged in any military service. Considering that this James Joseph wasn't required to register until September, 1918 and the war ended in November, 1918, it makes it less likely that he was drafted. If the man in the 1930 census is the same one, it says he was not a veteran.
If he was naturalized, there would be a record of it, but not all of them are available online. Do you have a passenger list of his arrival in the US?