Yes they are! But, the licenses and permits aren't just handed out to anyone! Lots of hoops to jump through to acquire those permits.
They are legal, with a license that requires a lot to get, and the feds can demand to see your weapons at any time for any reason, among many other things... I highly doubt this guy legally owned these weapons.
More likely they were supplied to him by a 3rd party, or he bought them on the black market, or he converted semi autos to fully autos.... My money would be he was supplied with them.
Time will tell