“His people” was not referring to Paul’s people but to the quoted verse which speaks of God’s people — “Hath God cast away his people? God forbid...”
Not so. The "his people" are the "Israelites" of which Paul is one. Read it:
"Hath God cast away his people? God forbid. For I [Paul] also am an Israelite, of the seed of Abraham, the tribe of Benjamin" [Romans 11:1]
AMEN!