"Free Palestine, F Israel" being treated as a threat is consistent with how all other Palestine/Israel speech is treated. E.g. in the UK if you said that in public you'd be considered a terrorist sympathiser (which is criminal). If you said it in Germany you'd be considered a Nazi (which is criminal). If you said it in the USA, they couldn't directly criminalise you based on speech but they'd find something else, like public nuisance or being a terrorist. So I'm not really surprised by this at all.