He's one of the few scientist-astronauts selected in 1967 who had to wait 18 years before getting a chance to fly!
Only Don Lind had it worse: 19 years!
Anthony England (capcom during Apollo 16) also had to wait 18 years.
But you have guys who actually flew more than once, even after waiting so long:
Bill Thornton, Joe Allen (great EVA's during STS51A) and the amazing Dr Story Musgrave and his 6 flights!
What I don't understand is what Bill Lenoir did: he gets to fly a mission but can't perform an expected EVA (for technical reasons) and after, quits flying status so won't ever spacewalk, while his buddy Joe Allen did a great one in 1984!
Was Lenoir so sick he got discouraged to fly again?

Raoul