It has nothing to do with how many chances you think Miami will get. There was FAR too much time in the game to predict that with any confidence, anyway. It's nothing more than common sense and easy math.
One of the articles stated that he was told to squib his kickoff attempts. For what reason I have no clue though.
You do not "chase" points until you have to. The final score of the game made it a very easy second guess, but you did not know at the time that is how the game would progress. If we have missed another 2 pt conv. It is very possible that Mia would not have went for the TD in which they missed, Kicked a FG and still had a shot at least to tie down by 8. Also, I thought it was a good move to see at the very least if Nugent was well enough to make a chip shot FG later in the game if need be.
If he goes for one than who is going to kick it? Nuge was injured and couldn't hit a chip shot, and Mangini didn't want to risk injuring him any further.