Let me start of by stating that this has nothing to do with me liking or not liking Morris as a HC canidate, this is mainly a post to point out what I believe are some poor justifcation for Morris getting a shot at the Broncos HC job.
Lets look at the situation that Tomlin stepped into in Pittsburgh, this was a team coming off a Super Bowl hangover season where they had to overcome Ben Rothlesburger attempt to become Evil Kenievil in the offseason, thet had lost their motivation in Jerome Bettis retirement, and had a rough season. In addition, they had lost their OC and OL coach in the offseason in Ken Wisenhut and Russ Grimm. However, the team remained largely intact from the Super Bowl team of 2005, led by vets on both sides of the ball. Tomlin kept the defensive staff (Dick Labeau) and kept the unit as a 3-4, even though many had thought since he was a "Tampa-2" guy that he would bring that defense with him, which was probably his best coaching move. Offensively, the team remained similar to the 2005 team with ball control offense and generally allowing Ben Rothesburger some more freedom for deep plays as Santio Holms started to blossum. The only key starter that they lost was Alan Faneca. Basically this team was still very talented, experienced, and did not require a overhaul, only someone who could help motivate the team week to week.
Now lets look at Denver situation, any coach will likely overhaul the entire defense, including players and scheme, the team is lacking strong veteran leadership and playoff experience as that there are only three starters on the defense (Ekuban, Williams, and Bailey) and one starter on offense (Hamiliton) that remain from the 2005 AFC Championship team. The offense will likely remain intact in scheme and players; however, there will likely be a fair amount of loyality to Shanahan and general distrust of a new coach, especially one that has limited experience. To expect Morris to be able to come to Denver, overhaul the defense, gain the trust of the offense, and get the entire respect of team will be a tough task to ask anyone, especially someone who has never been a coordinator other than one year in college.
The point being that much of the success of a coach, especially early on, and ones with limited experience, depends greatly on the team that they inherit. Look at guys that took over loaded teams and did well. Barry Switzer was widely considered one of the most stupid men to ever coach in the NFL, yet he won a Super Bowl, Bill Callahan took the Raiders to the Super Bowl. Both coaches took over veteran led teams that had a good amount of playoff experience and won inspite of themselves. Now I will not say that Tomlin is in the same class as Switzer or Callahan, but I do want to point out that his situation is similar in that they did not face a major rebuilding project. I have seen some disparging remarks regarding Lezlie Frazier getting a look at HC job because he inherited a good defense from Tomlin so that doesn't qualify as good expereince, I would argue he has more experience than Morris and if you use that arguement against Fraizer then the same arguement applies to Morris.