Can someone explain this quote to me please? It is about the novel "The Sun also Rises" by Hemingway. The quote is in the description

I've read this novel at least five times and have written several essays on it. I think the diction in the quotation itself is sloppy and a bit inflated. Although it is possible for something to be both "symbolic and symbiotic," that's a strange logical relationship. If you look up other sentences in which "symbiotic" or "symbiosis" is used, you'll see that the syntax here is awkward and unclear. I'm also unsure about Carson's claim that Hemingway "proposes" an "assumption": about the "mind of an expatriate" and "all that is wrong with modern civilization. . .in the novel." I don't see that Hemingway does that, Although he himself may have made sweeping claims about certain social issues in interviews and although his characters may do similarly, that doesn't justify ascribing a social or philosophical "propos[ition]" to a novel. There's an unsubstantiated assumption in the quotation itself. Do you have the rest of Carson's piece or anything besides this quotation? I've never read this one before. One possibility I do see here is that it's erroneous for Hemingway to make the expatriate figure symbolic of society's problems because the expatriate, by nature, self-consciously attempts to separate himself/herself from society but does not realize that he/she, in reacting against that society, is still thus a part of it. Beyond that, this quotation is loose and messy in my humble opinion.

I think he meant that you cannot use someone who has expatriated themselves from a country to be used as symbolic of that country or disagree with all of modern civilization.