Tassie's boyfriend Reynaldo is a "radicalized" Muslim who apparently stands as a counterpoint to Tassie's brother in the novel, a character who enlists in the US Armed Forces because he can see no other future for himself. Each of these young men is seemingly desparate to find a purpose for his life.
Can we say that Tassie is equally desparate? In what ways does Tassie exhibit extreme views too? Or is Tassie the "stable one" in a novel populated with people constantly on the edge of crisis and despair?
I pose this question just for sake of discussion - hoping to hear some ideas on this novel.
At this point in each society, neither character has a good way out. Chances are either choice is wrong, as the saying goes. Tassie and Reynoldo were both desperate, because they were put on the spot by their respective cultures and politics.
Considering that Tassie is the narrator using a well controlled ironic voice, and extremism she might display is circumstantial, the result of events and reactions to it. Nonetheless, within the circumstances, she does fall into extremisms of one sort or another, which is an important theme of the story: these extreme events result in extreme alterations of life and extreme reactions to the alterations and the events. Two of Tassies' comments in the early pages foreshadow her later extreme reactions:
Then we fell into a kind of hysteria--frightened, guilty, hopeless laughter I have never actually witnessed in women over thirty.
At this time in my life I was never late. Only a year later would I suddenly have difficulty hanging on to any sense of time, ....
I think this novel above all explores the way in which so many people reacted so differently to the aftermath of 9/11 and had to radically reassess their own identity and who they were as a result. You are perfectly right in considering Reynaldo and Tassie's brother as being both lost and needing meaning, although they try to solve this in very different ways. Tassie herself seems to oscillate between feeling lost at various points in the novel and striving towards finding her place in the world.
Honestly, I think that one could easily justify either stand. Given that literature is a place where interpretation is welcome, the reader simply needs to justify their stand by using textual evidence.
I think that, given the novel depicts life after 9-11, one could easily state that the novel is populated with people on the edge. I could also see the justification that Tessie is the one on the edge. She is the one who is coming into her own at a very troubling time.