Stanton's WORLD WAR II ORDER OF BATTLE lists the following for his unit:
752nd AAA Gun Battalion (Semimobile);
created in Hawaii, 12 Dec 43, from the original 2nd BN, 95th Coast Artillery Regiment, which had been activated at Camp Davis, NC, 17 Apr 41;
the 95th CA BN departed SF POE, 26 Dec 41; arrived Hawaii, 7 Jan 42; the 95th CA BN had no campaign credits;
the 572nd AAA BN was one of three similar units created from 95th CA BN, 12 Dec 43;
the 572nd AAA BN arrived Saipan, 6 Feb 45; arrived Iwo Jima, 28 Jul 45.
Air Offensive Japan, 17 Apr 42 / 2 Sep 45 Western Pacific, 15 Jun 44 / 2 Sep 45.
Location at war's end, 15 Aug 45, Iwo Jima.
Since his separation papers did not include the Iwo Jima campaign, one would assume that he was wounded on Saipan, and was in hospital there or elsewhere at the time of the Iwo Jima assault, and that is where he probably earned his Order of the Purple Heart.
I hope that this information fits in with your information.