That's the point. Since Welch died never having seen his contribution in the Fox program, it makes no sense to claim he was upset by it and undertook additional research. Further, the conspiracy theorists seem to think the Fox program was Welch's only onscreen interview. Welch gave interviews to David Percy for What Happened On the Moon? in which he does go into specifics on some of the supposedly anomalous features in Apollo photos. The premises on which the conspiracy theorists' Welch fantasy is based simply aren't there.

I suppose the next embellishment to this story will be that Welch allegedly called up Bart Sibrel just before he died and offered to blow the whistle on the whole hoax thing.