Up here in Northern Norway many Orcas come every year in late October for a herring-fest. It is quite common to go after them and have a swim, but it's very rarely a regular Scubadiver will get anywhere near them. They seem to be frightened by bubbles.
Snorkling works fine and you can get quite close to them. Noone has ever been hurt by an Orca here in Norway (nor the rest of the world to my knowledge).
You are not a competitor nor potential food for an Atlantic Orca as far as I've understood it. The Orcas here go after fish. On the west coast of California they have been known to go after seals and whale calfs. I guess if you've got a proper beer gut you could be mistaken for a calf.
Go swim with him. The fact that he's a loner doesn't make it a least bit suspicious. I'm sure he's kind. Good Orca... goooooood orc...
Do tell if you get near it. And if you get back.
Kyrre