I’m a retired U.S. Marshal, also and I agree with him. If you want to avoid immediate trouble don’t answer the door but trouble will come to you eventually The only question is do you want deal with a conflict at that moment or will you want it later. It will happen either way.
Re: 39 - I’m not sure what recourse there is for a COVID-19 door knocker if you don’t answer the door.
Walk around your house? They may be bumping up against curtilage vs. trespassing.
What happens if you are not home?