Different tactics work on different people. I was swayed from liberalism to communism much more by long form argumentation, stuff I had to read and really think about and examine, before concluding that my liberal beliefs were the garbage they were. Just saying "bad thing bad" to me would have made me roll my eyes and think you didn't have any valid arguments. And to be honest, current me doesn't blame past me for thinking that. Maybe that works on some people, but again, that's why there are different tactics. Yours is no more valid than VILenin's, and were it me on the other side, yours would be less valid than his by far. That's not me calling you anti-intellectual, but neither should you act like using reasoned argumentation is too high brow to influence anyone who isn't already a committed pro-Palestinian communist.
because again everyone understands that genocide is bad.
Clearly they don't understand that it's bad enough, seeing as this whole conversation is centered around the "calculus of deciding that a genocide is an acceptable trade-off." Many people who do recognize genocide is bad, still think "well, it's a complicated situation" or they have fallen for the both-sides lie and think that the Palestinians would be genociding Israelis if the zionists weren't doing it first. These are the kinds of lies that would be good to disabuse them of. Which is something we can do in numerous cases, since it has happened, and one effective way of doing that is to used reasoned argumentation with healthy rhetoric. Which is what VILenin was talking about. Coming in and saying "Nah, it's useless" or "that tactic doesn't work, but my short pithy one does" is weird and unhelpful. I'm not sure why you insist on putting down what he came up with.
It's not a slur any more than calling someone a Nazi is a slur. In both cases, the fascists chose the term for themselves and use it to self-identify. Leftists likewise use the terms with all the derision they deserve. Simple as. If I call a Nazi a Nazi, it's not a slur just because I think Nazis are evil and disgusting and are in need of redacting. So too with Zionists.
If someone is using the term to describe themselves, but they (correctly) think that settler-colonialism is wrong and that the state of Israel is a genocidal ethnostate, then they are misusing the term, according to both the vast majority of Zionists as well as the people who oppose Zionism. As always, what is antisemitic is the equating of Zionism with Judaism, it is not antisemitic or saying a "slur" to accurately use the term Zionist as an epithet. It's disgusting but unsurprising how the Zionists keep harping on this to try to make themselves out to be the ones being persecuted.