Nichiren says, "The scholars of the Tendai sect have interpreted passages of the three major works of Zhiyi, the Xanyi, Wenju, and Zhiguan, in one way or another, and have given plausible explanations. Their views, however, are as useless to us now as last year's calendar or yesterday's meal." (Showa Teihon 1634). The Rissho Kan Sho states, "Tiantai Zhiyi was in the audience at Vulture Peak, and though he speaks of the true intent of the Tathagata in appearing in the world,...he addressed an assembly of those converted by the provisional Buddha, and so Zhiyi did not propagate the transmission to the disciples of the original Buddha. He did not reveal the Wonderful Dharma directly. Thus it was not the Wonderful Dharma precisely as it is, and it resembles the provisional teachings." (Showa Teihon 847). In the Toki Sho it states, "Even though Zhiyi and Saicho propagated the Dharma as it was, in our age of the Latter Days of the Law, their teachings are like last year's calendar." (Kanjin Honzon Tokui Sho, ST 1120).
Then, why did Nichiren Shoshu adopt the Tendai method of transmission [succession through current masters or "lifeblood"]? You can learn about Nichiren Shoshu's false transmission here and refute it with Nichiren Daishonin's Transmission Through the Scrolls of the Sutra [Gohonzon, Lotus Sutra, and writings of Nichiren Daishonin]: