No, NASA is not hiring someone to protect the planet from them:
Though this should be abundantly clear by now—that NASA isn’t planning to launch an attack on aliens they don’t know exist—Shostak gets some colorful phone calls from those who want to believe.
“I have to say, people do call [me] and say, ‘Do you know anything about the Pentagon’s plans to defend Earth?’” he said. To be clear, Shostak does not know anything about ‘the Pentagon’s plans’ and thinks that even in some alternate reality where he did, the Pentagon wouldn’t waste time or money trying to save us. So please stop calling him.