Pleasant might be a legit contender for the job but I doubt Shula is.
Then why interview so many other candidates? Well, McVay knows Pleasant well enough but probably doesn't know any of the other guys as well. So I can see two reasons to bring other guys in.
First, that's the best way to find out if Candidate X is a better option than Pleasant.
Second, so you can ask the question "If you were a DC how would you defend the Rams offense?" (Great way to tap into the scouting of a number of other teams ...)
AlbaNY_Ram