It's not a cop-out if the blocking/ignoring is being done ICly. Samira's avoided responding to him because even if he's a heretic in her eyes, he's still Amarr of noble blood (or so he claims). It would be inappropriate for someone of her social status to make aggressive responses to him (though she has let slip a few minor quips, like the militia comment).
Yeah, Constantin's essentially stood up like a wall to him, but he wouldn't ICly ignore anyone. I seriously do look at Slaver Filth like that old guy who lives alone and is stuck in the 50s. You know, the guy who is racist, sexist, judgmental, and bitter about how society is changing from when he was a kid? Honestly, outside of a few trollish slips, that's pretty much been how I've treated him and he's played that part pretty well. If that's the aim, then he's sort of filling that gap.
He's sort of the Amarrian that even most Amarrians are telling to STFU, the Moral Reforms happened a millenium ago, grandpa. But that character ought to exist somewhere and be recognized that way. He has a corollary in every culture on Earth, the crotchety old guy that no one likes and everyone tends to ignore when he goes on about Communism and those damn [insert racial slur here] trying to take over the country. I think he definitely started as a troll, but as the character has grown, I'm not sure if he's stayed that way or if he's become more of an actual character. For sure, it's sad he can't change his name, otherwise we could take him more seriously.
Either way, I don't think Constantin could ignore him. When he's on task, Slaver's sort of a necessary evil in RP. He's that example of what happens when everything that can go wrong in a society does and produces an embarrassment.