Mm, I thought "Satan" was a role anyone could perform, not a name
I mean, in the NT and the OT, "the satan" (it's in fact the accuser/adversary, a title/function, not an actual particular name) can be anyone, from an angel part of God's court (Job) to even saint Peter (the gospel where Peter swears he won't allow Jesus to go to Jerusalem to be killed and Jesus sets him straight calling him out "Satan", it's right there).
So regardless of Christian tradition making "the satan" into a specific angelic being, the Bible actually gives no such basis for it (tempting Jesus in the desert is to spiritually train him for his mission, so that angel is clearly simply doing God's will and not out for some obviously absurd/impossible personal feat of getting Jesus to step out and worship him)
Even the movie, while on one hand making "Satan" a specific angel who looks like Pacino, on the other kinda implies this by having the reporter becoming Kevin's new "accuser/opponent/tempter", thus becoming his new "satan" after Kevin managed to resist Milton in the end.
That's my take anyway.