Joey,
Generally speaking I am not a big fan of converting par 5's into par 4's for tournaments. The main reason is because I feel par 5's are designed to hold a particular type of shot coming into the green. If it's a shallower, smaller green and the player wants to try for it in two as a five, no problem, they are taking on a certain risk for the potential of a reward. However, if the hole is converted into a par 4 and now players are expected to get the ball onto the green with a long club in two for a green not designed for that purpose that's where it loses some appeal to me. If the hole length itself is not changed, then I probably don't have as much as a problem with it, because a hole is a hole regardless if you call it a four or a five, but if you push the tees up slightly and call it a four that's when I have an issue.
Regarding the 13th specifically the green seemed large enough to accept a long club, however, so I don't really have too much of an issue with the decision. Also, the length of the hole at that elevation and for that caliber of player probably was ok, on the fringe, but overall I'd say ok. If they did make it a four the one change I would make would be to not cut off the fairway and to allow the bombers to be able to drive it as far as they want.
Interesting note in that I live 10 minutes from another Ken K. design called Orchard Valley in North Aurora, IL. You can see it posted on the sign earlier in this thread. Interesting in that it's North Aurora and Murphy Creek is in Aurora, CO. Also interesting in that the 13th at Orchard Valley is a 440+ yard par 4 that the landing area is cut off so that you either can't hit a full driver or you need to hit a 3 wood. For a hole that long it drives me nuts that you can't bomb it down there and you're forced to lay up on a long hole. It consistently eats my lunch and is the one hole on the course I would change if I could. Otherwise it's a great course and lots of fun to play.