I read this with the assumption that "nonimmigrant visa" applies to every category of visa listed here under "Nonimmigrant Visa Categories":
https://travel.state.gov/content/travel/en/us-visas/visa-inf...
Includes H and J. The letters used to refer to those visas comes from the subsections under 1101(a)(15)
This is a pretty broad swath of immigrants - H visa (worker and family), L1 (corporate transfer and family) and K1/3 (spouses of US citizen or green card holder).
What this limits are the truly temporary visitors - tourists, students, etc
From https://www.uscis.gov/green-card/green-card-processes-and-pr...,
> Adjustment of status is the process that you can use to apply for lawful permanent resident status (also known as applying for a Green Card) when you are present in the United States. This means that you may get a Green Card without having to return to your home country to complete visa processing.
Edit: the policy actually indeed mentions dual intent categories:
> USCIS reminds its officers that applying for adjustment of status is not inconsistent with simultaneously maintaining nonimmigrant status in a category with dual intent.
It does it in a way that will, for sure, cause confusion though.
[1]: https://www.uscis.gov/sites/default/files/document/memos/PM-...
https://codes.findlaw.com/us/title-8-aliens-and-nationality/...
With the caveat that I'm absolutely not an expert in this area and have no clear idea what changes have been made since, it's still highly informative to read this section and the carve-outs that were made at the time.
My current understanding is that the creation of "dual-status" visas (immigration act of 1990) paved the way for using the adjustment-of-status process established 8 USC 1255 for those particular visas (like H1B), and thus makes those visas less vulnerable to a change of interpretation by the executive branch. Contrast to, say, a regular tourist visa.
My current understanding is that the "carveout", as it were, is the creation of the notion of dual-status itself, in the 1990 immigration act. This made H1b visas both immigrant and non-immigrant visas, and thus eligible for INA 245.
For example, a law firm's opinion:
> However, the USCIS memo suggests the new policy may be less applicable to dual-intent nonimmigrant categories (e.g., H-1B, L-1 and their H-4 and L-2 dependents), where applying for adjustment of status is not inconsistent with maintaining status as a temporary visa holder. Dual intent means that a person can legally intend to reside temporarily in the United States for purposes of their temporary H-1B or L-1 work visa and simultaneously intend to apply for a future permanent residence status. Dual intent is a well-established concept in business immigration law, with many decades of support in federal law and regulation. The USCIS policy memo does caution that maintaining H-1B or L-1 dual-intent status alone is not sufficient, on its own, to warrant a favorable exercise of discretion. The USCIS officer must still weigh whether or not to exercise discretion in approving the adjustment application, but adjustment applications have always been discretionary.
https://www.quarles.com/newsroom/publications/top-5-things-t...
"Nonimmigrants, like students, temporary workers, or people on tourist visas, come to the U.S. for a short time and for a specific purpose. Our system is designed for them to leave when their visit is over. Their visit should not function as the first step in the Green Card process. "