You have a point, but Frost did say rumors were 'totally false,' and I don't know if an AD is going to confidently say things like 'he's staying' when it could really end up as egg in his face if/when Frost would leave.
Basically, we have Lars saying Frost to NU is a done deal on one side, and then the UCF AD saying 'nope' on the other. I honestly don't know what to believe, but part of me thinks if it was happening, we'd have a better indication by now. I remember hearing from several people that Pelini was a done deal right after Osborne axed Callahan.