If you're referring to SB 239, which passed in 2017, it did not decriminalize spreading STIs. It converted knowingly transmitting HIV to a misdemeanor, with the penalty changing from 3 years in prison to 6 months.
Effectively, it removed the special-cased extra penalties for HIV, and brought it in line hepatitis, syphilis, etc.
At one time, contacting HIV was only a matter of time until you developed AIDS, after which you could expect to have a life of increasing suffering and early death. A large part of your sex life is permanently eliminated, lest you spread the virus.
Today it is entirely possible to contract HIV and not develop AIDS. Should you develop AIDS, the prognosis is significantly less grim. It is also possible to maintain normal sexual relationships without causing viral spread.
Since HIV is no longer a death sentence it no longer makes rational sense for the legal system to treat it as one.
On an even more positive note, mRNA research is amazing and there may be an HIV vaccine as soon as this decade. The last person to die of AIDS may have already been born!
> A large part of your sex life is permanently eliminated, lest you spread the virus.
Please tell us who you think is willing to have sex with someone carrying HIV.
(And stabbing someone non-lethally can also be a misdemeanor, by the sounds of it: https://www.shouselaw.com/ca/defense/penal-code/245a1/)
Enough people that a major dating platform has a profile section dedicated to it.
https://help.grindr.com/hc/en-us/articles/230077107-Undetect...
Have you never heard of PrEP?