In the US, the Supreme Court ruled that credible threats are not free speech. Doesn’t matter who the threat is against. Other countries, I’m not so sure.
I think the Secret Service actively investigates threats to the president and other high ranking officials. Your neighbor would have to file a complaint with the police.
Honestly I dont think either of those things were ever legal in the USA. At best its a criminal threat or assault and at worst it can be conspiracy to commit a crime.
The only way that would be legal is if the courts found it to be hyperbole, such was the case for a protestor in Watts v. United States in 1969.
Enjoy your visit