How can changing Nichiren's Buddhism be "read in terms of Nichiren's Buddhism"?

Nichiren stated very clearly that "Shakyamuni Buddha resides in the hearts of those with sincere faith".

April 17 WT (1998), speech by Daisaku Ikeda delivered March 13, 1998:

“In contrast, this Gosho passage states that Shakyamuni Buddha resides in the hearts of those with sincere faith. Read in terms of Nichiren Daishonin’s Buddhism, “Shakyamuni’ here refers to the original Buddha, Nichiren Daishonin himself.” p. 12