That’s a strawman. There’s no illegal words in hate speech laws like the one in question. There are illegal intents, illegal publications, etc. - those already exist. To go back to my previous example: “fire” isn’t an illegal word. But shouting “fire” in a crowded theatre (where there is no fire) is an illegal action intended to cause harm.
Thinking genocidal thoughts, even saying genocidal ideas aloud, all are ok under most western hate speech laws. The line is usually in publishing or broadcasting genocidal ideas.
Hate speech laws are on a slope, and at the bottom is of that slope is authoritarian thought police territory, for sure, but it doesn't seem that slippery a slope from where i’m standing.