okay but if we ignore real life factors and try to create a canon compliant explanation for this i feel like it would be along the lines of:
martin is ignoring the way heâs acted up to this point and is putting his fear of losing jon first. pinning the blame on jon via this accusation could be (and is implied to be part of) martinâs way of convincing jon that taking jonahâs place isnât the right decision. now, the way that martin places the blame on jon may have been defensive and/or reflexive because i think the way he tries to guilt jon here is unintentional and more of a desperate plea for jon to not go through with his plan
it might also be worth noting that its been shown before that martin has been âfavoredâ by the web which is known for manipulation and all so it wouldnât be out of character for him to purposefully or even reflexively guilt trip, especially in high-risk scenarios like an apocalypse (im not trying to paint martin in a bad light im just trying to look at this objectively)
i also donât think that martin realized that he was also enjoying this revenge spree because if you ask any person who wants to preserve any semblance of a moral compass and an appearance of morality (even inwardly) would say that they donât enjoy revenge, that they didnât enjoy seeing âpeopleâ in pain, even if it was in retaliation. the way heâs ignoring his own actions/attitude may also be subconscious since there probably isnât a lot of time for introspection in an apocalypse (martinâs domain notwithstanding) and when faced with how bad or accusatory âkill billâ sounds (especially in the context of this dialogue), martin deflecting the blame here may have been him getting defensive about himself in trying to justify why jon shouldnât âsacrificeâ himself
âIâve been out there with you. I saw the kick you got out of making them scream for once.â
what martin said here also struck me as incredibly hypocritical (in a similar âthe character is good because it has flaws and makes mistakesâ way) and i feel like this line really drives in the fact that martin was grasping at straws to get jon to not do it and (possibly) accidentally accuses his boyfriend of being a monster, which is something that we know jon struggled with even before the apocalypse so having martin throw that indirect accusation at him also made jon get defensive hence bringing up the kill bill instance
OKAY SO NOw, heres where i actually get into how jon responded to this (lmfao that was such a tangent i have so many thoughts and so little places to put them im so sorry)
like you mentioned, jon doesnt respond to this and it was just never addressed again and as you pointed out. the audience largely takes from this interaction that jon is solely at fault here because it ended with jon walking away instead of trying to deny and defend himself and say no, martin, i did not enjoy it. i feel like some part of this has to do with the fact that jon feels guilty that he did, in fact, enjoy it. that what martin said is true, but to admit this out loud would be too much for him to handle
another part of this could be that jon is so afraid of directly attacking martin, what with how tentative their relationship still is, even with how much affection they express already. jon is, as we are reminded time and time again, constantly aware of everything going on in the apocalypse. he probably Knows to some degree that martin also enjoyed the killing spree but chose not to say anything because it would come off as unnecessarily aggressive and not just how he would defend himself, and it would also kind of admitting to have invaded martinâs privacy, a boundary that jon puts in a lot of effort to respect
personally after reading this through 3 times i can safely say that this doesnât really make sense but itâs 1am and i just had to get this out of my system