David Noordewier said he was fired Feb. 27 for posting the message, which he said was a joke and not a threat.
"I told them that this was crazy," Noordewier told The Flint Journal. "It's not like I have a fighter jet in my backyard to drop a bomb with. Then they escorted me out to the parking lot."
Noordewier said store officials had him sign an acknowledgment that he was fired for "gross misconduct — integrity issue."
Wal-Mart spokeswoman Kory Lundberg confirmed that Noordewier no longer worked for the company but would not discuss why.
Unemployment officials said Noordewier did not qualify for benefits because he had made a threat.
Noordewier had a near-perfect work attendance record and once received a personal thank-you letter from the company president over compliments from a customer he once helped.
He said he thinks a co-worker disliked him and pointed the MySpace page out to his boss.
"If you have a MySpace site, you better act like you're a politician," he said. "Be politically correct and don't try to be funny."
MySpace is owned by News Corp., the parent company of FOXNews.com.