This is how they justified it:
Senate Bill 145 ends California’s anti-LGTBQ discriminatory treatment of specific sex acts regarding sex offender registry law. Under longstanding California law (since 1944), if an adult has voluntary penile-vaginal intercourse with a minor aged 14, 15, 16, or 17 and is up to 10 years older than the minor, the offense is not automatically registrable. Rather, a judge has discretion whether or not to place the defendant on the sex offender registry depending on the facts of the case. By contrast, if the act is oral sex, anal sex or sexual penetration, the court must place the defendant on the sex offender registry regardless of the facts of the crime and even in cases where the prosecutor and judge do not want to place the defendant on the registry. This distinction in the law is irrational and discriminatory towards LGBTQ young people. For example, if a 19-year-old and 17-year-old couple have voluntary oral sex, the 19-year-old must be placed on the registry. But if it’s vaginal sex, the judge has discretion to place the older party on the registry or to keep them off. SB 145 ends this irrational distinction by treating all voluntary sex the same way that the law currently treats penile-vaginal intercourse.
---
How about just making the first one also registrable? Dingbats.