You misunderstand. There are two people referred to in my post.
My ex was a long term non-progressor. He went without taking meds for close to 20 years when I first knew him, his CD4 remained stable but his viral load was not undetectable. I've since lost touch with him around 10 years after I knew him. As at when I lost touch with him, he still had not started on meds, but and I cannot tell you if it has remained that way. It was through him that I got infected.
My husband is the one who is an elite controller - i.e. he tests positive for HIV. However, even without medication, his viral load is undetectable - and remained that way for the last 24 years. That said, in the last few of years, his CD4 is slightly lower than average and his dr suggested he start on meds about a year ago, and it seemed to have bump the CD4 up.
Trust me, it was a bit of a mind-fuck for me that the first 2 HIV+ people I knew had such an unusual presentation of HIV.
So, if you test negative, it just means you have not been infected by HIV, it does not mean you're a long term non-progressor or an elite controller as both will test HIV+. I think I have read about people who are HIV resistant - which is what I think you are referring to (i.e. do not become positive despite repeated exposure to HIV), but honestly, I imagine there would be very very very little data out there should they exist