This sounds like the source that gave the Champions/Chief leak was someone he found credible, and well, wasn't in the end.
I could still see Chief as the final character, though.
But yeah, it's over. Vergeben has an overall decent track record for Smash and all, but DLC isn't his area. Like, the only other possible thing is that his source poorly explained the Champions stuff and somehow was referring to AOC content. So, you know, that 1% chance in hell it was a misunderstanding. I wasn't aware he was backing that entire leak either, just something(I was avoiding spoilers). I figured out he said Chief, but not the Champions. Nonetheless, best to just let it go. Bad source, etc. It looks like Chief is even more hard disconfirmed. Which is sad, cause he should've at least gotten something in Smash(Spirit, Mii Costume). It's the last the three big series Microsoft owns as is, after all.