As I understand it, a linking verb connects the subject to a noun that redefines it OR to an adjective that describes it. In this case, "in our society" does not "rename" xenophobia, but it does describe it.
For example, "Bob is the chairman." "Bob" and "the chairman" are two ways of identifying the same person, so "is" is a linking verb here.
"Bob is hungry." "Hungry" is not another name for "Bob", but it is an adjective that describes Bob. "is" serves as a linking verb.
An interesting rule of thumb I just stumbled across is, Try replacing the verb that you think may be a linking verb with "is". Does the sentence still make sense and convey a similar idea? If so, it probably is a linking verb.
"Bob feels hungry." Replace "feels" with "is": "Bob is hungry." Yes, it's still basically the same idea. "Feels" is working as a linking verb.
"Bob feels a pain in his foot." Replace "feels" with "is": "Bob is a pain in his foot." No, that doesn't make sense, definately not the same idea. "Feels" is not working as a linking verb.
In this case, "Xenophobia IS in our society." Yes, that makes perfect sense and is a similar idea. "Remains" is working as a linking verb.