I've read that (can't find the citation) "Death to X!" is basically like a "God damnit!" curse, e.g. they'd say "Death to this traffic jam!" if stuck in traffic, but western news reports fail to bring the context. Again, maybe not true.
I wonder if they should just change the phrase to something like "I wish kittens for Khamenei!", but letting everyone know off-channel that this sentence means wishing him ill. How you gonna deal with that, Zuck?