Pat Boone did play a role in early rock, but it would be hard to make a case that he belongs in the rock hall of fame. When rock music first began to be popular circa 1955 or so, most parents hated it. It was raw and gritty and not like the smooth pop ballads that Sinatra, Como, Doris Day, and others were recording. Boone sort of bridged the gap and made rock & roll tamer and more accepted by parents. He did tame cover versions of more hard-edged rock songs by other artists, such as Fats Domino's "Ain't That A Shame" and Little Richard's "Tutti Frutti".
Pat's versions were often huge hits, as were his mainstream pop songs such as "Love Letters in the Sand" and "Moody River". But they could be called rock only in the sense that the Carpenters or Bobby Goldsboro could be called rock. They were Top 40 pop hits rather than rock.
In the case of Pat, the main argument for his importance in rock history is that he made rock more mainstream by toning in down, and recording softer hit versions of established rock songs. He played a role in early rock, to be sure, but not in the truly creative way that Chuck Berry, Roy Orbison, and Elvis did.
Being a Christian may well be a drawback but I doubt Pat would be in the rock hall of fame in any event.
You are correct, your knowledge of American music history sends you to the head of the class. Interesting, in all of the posts on this subject of "rock" not once did the name Eddie Cochran come up. He was voted into the Rock n Roll Hall of Fame early along with Bill Haley, Bo Diddley, Jackie Wilson, Marvin Gaye and others.
The Beatles, The Rolling Stones and many English hit makers claim Cochran was their inspiration. While he was an American artist, he is largely unknown here except by the music industry. In England, where he died in a tragic automobile accident in 1960, Eddie Cochran is considered on the same level at Elvis and Buddy Holly there.