Nostr is not safe and it is not safe by design. There is no way to keep ISIS off of Nostr. Tools are being built to make your feed and interactions more comfortable and free of you dislike but there is literally zero anyone can do to remove someone from Nostr or to stop them from posting said information unless such violates the law and it would still be upon the law to stop said person. ElonJet is posting publicly available information. Anyone who would endanger Elon or his family would certainly be very capable of getting this information without ElonJet. Honestly it would be a bad criminal who depended on second hand information to plan a high level kidnapping or assasination