YTA
In part, not just for the reasons other's have pointed out, but because of this:

Anna expressed a desire to introduce Jamal to them now that things were getting more serious between them... I may have no problem with Jamal, but they absolutely will, and even when the relationship ends they won't forget it.

Your daughter explains she is getting more serious with a boyfriend you say you have no issue with, but, in the next breath, you are hedging on their relationship ending, not moving forward.

You also opened with:

The problem is Anna is rather naive about the community she lives in.

While I am delighted to learn that whatever racist town y'all are living in has a newer generation who are more inclined to be better humans than their elders, do you really think your own daughter at age 19 doesn't know the biases of her grandparents and her neighbors??? For one thing, I promise you Jamal is well aware of it like his life depends on it.
She is likely pushing this issue precisely because she is invested in the relationship & because she may love her grandparents but also see their flaws as not something to pander to but confront.

I know, no advice. But, for chrissake, talk with your daughter openly. Hear her side. She may well be more comfortable ending a relationship with her racist ol' grandparents than you can handle confronting your parent's shitty beliefs. I mean, did you at least defend your wife's right to wear a skirt of whatever length she wanted, or do you tolerate every ridiculous judgement they throw around?