From all reports Otz wasn't promised the head coaching gig (per CW and Jeremy). TJ took the job to be an assistant under Fred Hoiberg to either be in position to be ISU HC when Fred left (~3yrs) gain more experience to get a HC gig and finally live in Ames. Situations change and thus Otz and has no idea what type of relationship his new boss and him will have or if they would even want him on the staff.To just say be happy and go to work is an oversimplification, especially if TJ or the team, thinks Otz is as or more qualified to be the HC than who they hire.
Secondary concern TJ leaving after next year may be worse for recruiting long term. OTZ being forced to stay a year building recruiting relationships and leaving could end up like Matt A situation where they eliminate ISU late, de-commit and follow him to his next stop except this time ISU won't have a preseason top 10 roster returning.