The sketch exists. It's available on YouTube. Sweet's whole "I haven't seen it, therefore it doesn't exist" thing is both indicative of arrogance and autism. There are lots of things I haven't seen that I know exist. He's also argued for people who've linked him to the damn thing, that it's fake. That's right, he thinks NBC colluded with a small, third-rate university to produce a fake sketch for the sole purpose of discrediting him. There's evidence that narcissism and autism are on the same spectrum, and for Sweet to think that he's so important that ASU would do something like that is proof in that direction. He's incapable of being original, so I have no doubt he stole the idea from the sketch (and he's such a TV junkie that I'm sure he watched SNL back in the mid-90s when it was really good). His confession is on file, as referenced by the guy who told him to stop contacting him. It's not like they needed the plagiarism incident to kick him off the Herald staff, they had plenty of other reasons to can him, that's just what they chose to use.
EDIT: A while back, just for kicks, I compiled a list of things Sweets believes. The sketch being fake was one of them.