Not Everything Odysseus Does is Supposed to be Justified (and that's the point!)
(on killing Eurymachus)
I really enjoy Odysseus as a character, and I love that Penelope doesn't hold him in any condemnation. I think it is an enjoyable story arc. If I could change one thing in the story, it would be to have SOMEone, (Telemachus, Ctimene, or Athena in a more significant way) fail to forgive Odysseus, or at least check him in some way, and serve as a foil for Penelope.
That said, I think the narrative is very clear on Odysseus's moral greyness, but I'm constantly surprised by how many people are defending and justifying all of Odysseus's actions (typically with doxing himself being the one thing people will admit to being the "wrong choice"). It's common for people to talk about how he had no other options, how he's a victim, refer to the entire time he was gone as "torture" for him, and demonize anyone who didn't serve Odysseus's goal of getting home to his wife.
I think many of his actions have different levels of moral greyness, but the two that stick out to me as actions that the narrative itself views as morally wrong are sacrificing his unknowing men to Scylla, and killing Eurymachus (the open arms suitor)
People have talked a lot about Scylla, but to me one of the important things is that within the story, parallels are explicitly drawn between Odysseus and Scylla, Odysseus is unwilling or unable to defend his actions "I can't" and it's stated multiple times throughout the story that he would (and did) sacrifice his entire crew to see his wife again.
For Eurymachus:
Over 100 suitors were "involved" in Antinous's plot, surely different ones had different levels of ambition/comfort with the plan, with some only paying lip service to it to avoid becoming a target themselves
Antinous's entire plot was only conceived of because they thought Odysseus was dead. Not because they thought that meant they could get away with it, but because Penelope was intentionally meddling with the line of succession outside of her power. If Odysseus isn't dead, then he IS king, and the suitors have no reason to pursue it.
All the same, killing Antinous still makes sense, he was actively planning and wanting this, you can't just let him live after that. But again, it changes things for everyone else.
Saying, "you're back, the person who made the plan is dead, spare me I have no quarrel with you" is completely reasonable. I've seen people arguing that the open arms thing was in bad faith bc Eurymachus and the suitors just wanted to save themselves, but it's no different than Odysseus trying to reason with Polyphemus or Poseidon.
It's particularly interesting that in the song "Odysseus" that Odysseus gruesomely kills someone who is unarmed and begging for forgiveness, and then IMMEDIATELY after, armed suitors refuse to surrender to Telemachus and say "after seeing what the king will do to us, we wouldn't dare" and attack Telemachus. You can ABSOLUTELY argue that Telemachus being attacked is BECAUSE Odysseus refused to show mercy, and if anything happened to him, Odysseus would bear part of the blame. And it's possible the text is even trying to say this outright.
Killing 100 unarmed men outside of war after they've attempted to surrender is just never a justified action I'm sorry. I'm not saying that I "hate" Odysseus or Epic, but it's indefensible, moreso than any other thing he's done. It's akin to Poseidon drowning Odysseus's fleet.
Tldr: Odysseus becoming the monster is a beautiful and enjoyable narrative, but if you're justifying his actions, or trying to argue that sparing suitors would have been a mistep, then you missed the point.