Alright. I'm HIV negative. However, I'm a Gay Black man, and my category/profile group is more keen/common to be HIV positive judging by statistics and reports. So I have to add my two cents.
OP, your profile says Vietnam, so this might cause some friction/contradictions, as I'm in North America/United States, and laws are completely different here.
But to my knowledge, (there are so many terms and secret words for this) Bug Chasing/Gift Giving/Poz Breeding etc. (Someone who is HIV positive, [or has full blown AIDS virus in some cases], who is open to transmit their virus to another person, with the other person currently being HIV negative, and with both parties being in agreement/understanding of what they are doing and thusly having unprotected/unsafe/bareback sex. With the end result of the HIV negative person, now being diagnosed positive. Possibly this is done by guys who are very sexually promiscuous, to eliminate the worry to find guys who are clean/HIV negative, or receiving a shock HIV positive diagnosis they weren't expecting.) is a federal crime here. It is a federal law that anyone who is HIV positive to have unprotected sex (protected sex doesn't usually fall under this rule, and people who are HIV positive usually in many jurisdictions, do not have to disclose their status for protected/condom sex, although me personally I feel someone who is HIV positive should inform their partner regardless but this is what the law states) without disclosing their HIV positive status first, and/or engaging in sex to purposefully transmit the virus; is illegal. Whether people actually get into trouble in the end, meh, but that's the law here in United States.
Okay, so having said that, I'm going to not agree with this. I'm HIV negative, but I wouldn't outright judge a guy at all who was positive. (Although yes there is stigma with Poz guys in the gay community, but people fucking suck, so forget them) But a guy who willingly wishes to make guys who are negative, positive, (even if the negative guys are content with this) is very concerning, and imo OP, is not a guy you should mess with.
Next, supposing you do agree to this, from what I heard, guys who engage in Bug Chasing/Gift Giving/Breeding, (I'm sure it's not the same in all cases but just saying usually) yes you will inevitably become positive, but your viral load counts (as the person breeding you also was engaging in the Bug Chasing/Breeding circuit with other guys causing the virus to act in a dangerous way) might cause you to experience symptoms faster, possibly get you sicker, you will have a much more difficult time battling the HIV virus etc. and this is not good. (as you guys are intentionally causing the HIV virus to multiple and spread etc.)
In addition, it could be that persons viral load is very low/they are undetectable, so you have a very, very low risk and chance of getting the virus. So all of this would be redundant, foolish anyways.
Also, as time goes on, (although HIV stigma is very much present) and we hopefully race to find a cure for HIV/AIDS sometime, the HIV virus is being studied and examined more, and the virus (although still very much present) is little by little being expurgated, and this is shown as we have things like Prep/Pre Prophylactic Exposure preparation medications (pills that remove the virus if you came into contact with it days/weeks/months ago etc.) and god forbid you are diagnosed HIV Positive, unlike in the 80s/90s, although it's not something you would want to have, it's something you don't have to let define who you are as a person, and there is very good HIV medications and treatment now. So yeah.
Finally, usually guys who advertise they want to Bug Chase/Gift Give/Breed, are also down to do other very scary, unmentionable acts/services. Which include possibly things I can't mention on LPSG, like body mutilation, torture, illegal stuff etc. Again, just being blunt and honest, but yeah.
But that's just what I feel OP. Thank you.