aren’t 5 kills needed to become an “ace”...Yep. I can't seem to find his total number of aerial victories anywhere. He flew 70 missions in Korea and another 110 in Vietnam. It doesn't seem hard to believe he might actually be an ace, just not with verified kills in that one engagement.
And I say 'verified' kills because while he got credit for 4 and 2 possible damages, Soviet records released after the cold war show that only 1 of the 7 they sent after his flight returned; he may well gotten 6, but that would still be an unconfirmed number and not qualifying as an ace.
I've tracked down a couple interview transcripts with him, and he doesn't mention any other aerial victories (sounds like this Vietnam service was largely air-to-ground) so my best guess is he officially has the 4, with 2 more possible/likely.
The man had a heckuva career, including being the first to land an F4 Phantom after a double engine fire (which allowed for inspection of the aircraft which in turn allowed for changes to help prevent them in future) and also suffered a crash where his neck and back were broken.
Wikihahahahahahapedia, in its list of air-to-air victories in Viet Nam, does not contain any by Royce Williams ... the only “Williams” was a COL D. Williams, USAF.