Why psychopath stabbing people by hiv+ needle is a only myth?

I had read some of Dr's response to questions about hiv+ psychopath trying to infect people by placing needlestick with their blood and your comment on these questions are all "no risk" base on the fact that hiv cannot survive outside the body. However I had read some documents stated that hiv can survive outside the body ranging from 1 minute to around 10 minutes. If a hiv+ psychopath place the tainted needle there and someone sit on it(or simply the mad guy stings somebody with it) in less than 2 minutes after the psychopath polluted the needle with his blood, why there is not risk ? Please understand I am not challenging your qualification. I am pretty confused by those information about the infectious of hiv and I just want to get some answers and real fact from professionals. Please assume the case mentioned above is true and don't just response me with" There is no mad people like this and even there is, no people is unlucky enough to be stabbed while the virus is still about to infect!"
Have a nice day :>

[Vance2335]

We do not address "what if" situations here. This is an anxiety driven question that has no merit. Sorry that is not what you are looking for but it is the truth.