that was a basic f-up from Kishi, back then he hadn't yet thought of Susanoo, or Amaterasu or anything like that, same goes for Yamato and wood, Kishi didn't know back then that Yamato was gonna appear so Hiruzen does not know his techs
Hiruzen does not know KGs from Konoha (that was astablished later on) but since back then the only 2 were Byakugan and Sharingan (which had no techs by themselves yet) Kishi completely exaggerated and blatantly stated that Hiruzen knew all the tech's, he in now however stumped because he created empty hype around him and no ammount of techs from Konoha (that should be able to know) is gonna get him up on to the level that he should be on (the other 3 Hokage)
so the only choice for Kishi is to ignore Hiruzen all together or give hi m an asspull power, which, considering he was hyped by ''knows all jutsus from Konoha'' would just be weird, the normal everyday techs from Konoha do not put him up on Hokage level
I think Kishi is at this point in time just trying with all his might to think of a way to defeat the OP Madara and not make it look like a completely random asspull