That's it. He basically says, I could prove that I was right but I'm not willing to give up my source. Not an apology, just trying to cover his ass.
"To prove at this point my story was accurate other than the using the word “steroids”, I’d essentially have to compromise and potentially even “out” my sources. If there’s one journalistic item I’ll continue to do right by it’s that I’ll never under any circumstance turn on a source."