As an immigrant founder of a small company, America no longer seems to me like a safe environment. The entire political culture has become nothing short of toxic, and crimes like this out in the open makes you question why would an immigrant come to US to start a business if they can get murdered like this? The fact that this happened in one of the safest areas in New York, makes you wonder if city life even worth it? May be he should have owned a gun? So many questions.
How is an immigrant status related to (presumably) business/political issues the victim had? Do you believe that it is safe anywhere when you make deals and conflicts with people whose values do not include lives? Remember terrorism acts in both US and EU in last two decades. I'm assuming you're honest in your anxiety, but this rhetoric sounds just alarmist. As if some cityname was equal to a bunker-like safety zone and not just street-crime protecting area. What did you expect from local authorities to do to prevent his sudden murder? Put a wall around the city and profile everyone for a week to allow an entrance? Nobody and nothing can protect you from a random professional hitman, neither a personal protection service nor a gun, but as a regular person who does a legal business in a first world you're damn safe everywhere.
Hope his family finds some answers.