Wisdom of shooting down UFOs (Unidentified Floating Objects)

What if these objects are “booby-trapped” and contain a biological or radiological payload? What if they contain billions of anthrax spores or plague bacilli? Why can’t the air force use low speed aircraft towing nets to enshroud the object with extra weight causing it to sink back to earth rather than blow it up in a manner that our adversaries think we are dumb enough to do? Just askin’.

My nephew asked the very poignant and intelligent question of whether there is any danger to blowing up and releasing a biological payload at 50,000 feet? The answer is that if carefully designed and notwithstanding the incineration temperatures of the explosion, the payload could be packeted in a manner to disperse, say, anthrax powder, into smaller bomblets that could have a much higher sedimentation rate, allowing them to fall to a lower altitude before being released and scattered. The further issue to remember is that biological weapons are often as much an instrument of psychological as of physical terror. The simple identification of an anthrax payload would have a predictably shocking effect upon the population at risk.

It seems that all bets would be off if the payload contained 100kg of dispersible long-lived radionuclides. 

Unless I am missing something, I simply find it reckless to blow something out of the sky when you have no idea its payload and when you may have the option of capturing it by weighing it down with a heavy net or some other methodology. I realize that aerial refueling occurs at about 35,000 feet and certain military helicopters have a ceiling of about the same altitude, but there may be a way to capture these high altitude, slow flying objects with slow flying prop planes - NASA has shown the feasibility of such vehicles with its Helios program.

https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-068-DFRC.html

NASA Armstrong Fact Sheet: Helios Prototype

Helios Prototype is a remotely piloted flying wing aircraft developed under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project.

www.nasa.gov