But, your scenario is not what happened. Elimelech left his country in trying times, went to Moab, his sons married, he died, the sons died, and Naomi decided to return to Israel. Ruth wanted to go, but was not required to go. She arrived penniless and made her living gleaning.
She was advised to take advantage of her rights to re-marriage and she did so. It worked out.
She was a foreigner and her only relationship to Israel was that her husband had married her in her own foreign country.
It was open and fluid with few legal hangups.
I can’t find the exact situation in US immigration standards, but for a foreigner already INSIDE the US whose spouse has died it says this:
“If the marriage has ended because you got divorced, your US citizen spouse has died, or due to abuse in the marriage, the foreign-born spouse may be eligible to apply for a waiver of the joint petition requirement. However, these waivers are very difficult to get. “
Doesn’t sound to me like Ruth ever would have gotten inside the US.
Now, you could make a case for a different equivalence: There are also millions of Mexicans who are in this country legally. It would therefore be wrong to create a situation in which they would suffer discrimination because of the illegal border-crossing of others, just as it would have been wrong to discriminate against Ruth in the gleaning because she happened to come from Moab.
A good example would be a friend of mine from Peru who earned his citizenship, but still has to provide his documentation everywhere he goes.
Again, I'm not siding with Uriel--I'm saying that anyone who thinks this is a black-and-white Biblical issue is being overly simplistic.
Shalom