lol, Yes, Non-Immigrant visa holder are not require to register, but you misunderstand the definition of non-immigrant visa.
https://travel.state.gov/content/travel/en/us-visas/immigrate/the-immigrant-visa-process.html
Immigrating to the United States is an important and complex decision. In this section, you will learn about who may immigrate to the United States, the different types of immigrant visas, the required forms, and the steps in the immigrant visa process. Because most immigrants receive visas in the family or employment based visa categories, they are a key focus of this section.
To be eligible to apply for an immigrant visa, a foreign citizen must be sponsored by a U.S. citizen relative, U.S. lawful permanent resident, or a prospective employer, with a few exceptions, explained below. The sponsor begins the immigration process by filing a petition on the foreign citizen’s behalf with U.S. Citizenship and Immigration Services (USCIS).
Basically, every visa that leads to Permanent Residence in the US are immigrant visa, which mean holder of Family Base, Employment Base, and Asylum Base visa are all immigrant visa.
Non-Immigrant Visa, on the other hand, is for person who are not US Citizens (Defined as Foreign Alien) to enter US with the purpose of temporary stays. A person must hold substantial ties to their home country in order to applies for a non-immigrant type visa.
In fact, the selection service actually define undocumented alien (with purpose to stay in the US but without any visa) must also register with Selective Service