The Passover is not a type of the passion
For if he had said: "As Moses made the Passover in Egypt, so must Christ suffer," it would have been undeniable that it had become a type of the Passover. Since he likened his passion to the serpent hung on wood, his passion would be a type of nothing else but this.
Greek
Εἰ γὰρ εἰρήκει· "Ὥσπερ ἐποίησεν τὸ πάσχα Μωϋσῆς ἐν Αἰγύπτῳ, οὕτως δε[ῖ παθ]εῖν τὸν X(ριστό)ν", ἀναντίρρητο[ν δ' οὖ]ν τι τύπον τοῦ πάσχ[α γεγ]ονέναι· ἐπειδὴ τὸ πάθ[ος ὡ]μοίωσεν αὐτοῦ τῷ κρ[ε]μα[σθέ]ντι ἐπὶ ξύλου ὄφει, οὐ[κ ἄ]λλου τινὸς ἢ τούτου τύπο[ς ε]ἴη τὸ πάθος αὐτοῦ.