Chris Roberts, founder of the security intelligence firm One World Labs, was blocked by United Airlines from his flight after a hacking tweet. The U.S. Federal Bureau of Investigation (FBI) immediately detained him and confiscated his electronic devices.

The problem began on Wednesday when Roberts tweeted that he can hack the airplane's network to deploy the emergency oxygen masks. This supposedly joking statement was taken seriously by the federal agency.

"Find myself on a 737/800, lets see Box-IFE-ICE-SATCOM, ? Shall we start playing with EICAS messages? 'PASS OXYGEN ON' Anyone ? :)" his tweet read.

The FBI pulled him out of the Syracuse, N.Y., airport and held him for questioning for four hours. It also seized his electronic devices, including his laptop, iPad, hard drives and other computer gear for investigation.

Roberts admitted that he learned to be more careful on Twitter after the incident, but he also expressed his disappointment with airline security. His team warned Airbus and Boeing years ago of the security flaws, yet he didn't see any improvement.

"I was probably a little more blunt than I should have been," Roberts told CNNMoney. "I'm just so frustrated that nothing is getting fixed."

But that is not the end of the story, because it seems that United Airlines doesn't want him on any flight. When Roberts attempted to board a San Francisco flight for his RSA conference on Saturday, airline authorities told him he can't fly.

"He had made public statements about having manipulated airfare equipment and aircraft systems," Rahsaan Johnson, United Airlines spokesman, told the USA Today. "That's something we just can't have."

Johnson clarified that Roberts was told hours ahead that he can't take his flight with them.

Though Roberts was able to book a last-minute flight with Southwest Airlines, the Electronic Frontier Foundation (EFF), an organization protecting the civil rights of digital technology experts, expressed their disappointment on the action of United Airlines.

"United’s refusal to allow Roberts to fly is both disappointing and confusing. As a member of the security research community, his job is to identify vulnerabilities in networks so that they can be fixed," EFF said in a statement.