If you want to quickly prove citizenship, a passport is what you need.
Yes, but there's no general requirement for a US citizen to have a passport, let alone carry it while in the US. Or really to carry any identification unless operating a motor vehicle on public roads, transiting an airport, or purchasing controlled substances like sudafed, etc.
The burden should be on DHS to disprove citizenship.
You are not required to carry ID when transiting an airport for domestic flights.
It will be difficult and annoying but you can fly domestically without ID.
It's no trouble to get a real ID licence as a non-US citizen. They literally have a process for this.
This article seems mind boggingly stupid. They are trying to create drama out of something that isn't there.
If you intend to reside in California, you need a California license within 10 days of establishing residency (assuming you drive); but if you're just visiting for a month, I think you can use your out of state or foreign license. If you've got some authoritative reference that states a temporary visitor (less than 6-month) to California needs a CA license, I'd like to see that...
Which is why this article is going at the wrong point. Real ID is meant for citizen and non-citizen alike.
You got your REAL ID because you were legally allowed to be here. They wouldn't have issued it otherwise. DHS approved your REAL ID so they have no reason to assume that if you a have a valid one you're not allowed to be here