Justice is ruthless in the Odyssey. Death is served easily for many transgressions, from inhospitality to poor manners to disrespecting the gods. Actually, because the gods were supposed to uphold standards in daily life such as hospitality, violating those rules was itself an offence against the gods. Once it comes to meting out punishment for such offenses, Homer’s characters pull very few punches.
Poseidon is unjustified in hounding Odysseus across the seas because his son Polyphemos deserved the blinding that the hero gave him.
Poseidon is justified in hounding Odysseus across the seas because although Polyphemos deserved the blinding he got, Odysseus’s hubris offended the gods and earned him Poseidon’s enmity.