I don't think it's that simple. The applicants would naturally want to talk to the SD, but they'd also want to speak to the owners and other Board members. Clement left Rangers because he didn't get support with transfers and he wouldn't want that situation again. The final decision would be Knapper's, but he'd have to make a case for it to the Board and that's the way it should be IMO.
Not all business operate the same procedures. Maybe in the sector you worked in the procedures where different to how a head coach is recruited. I may be wrong, but I don't think you were ever involved in recruiting a head coach for a sports team. Maybe things have moved on since you retired. I would suggest the interview is just a part of the process and how someone interviews isn't the only factor to be considered. Normally if an interview is done by a panel, each interviewer scores the candidate and has equal input at that stage. Post interview the entire process is considered and a first choice candidate (if there is one that is suitable) is given an offer. If they decline then you either move on to the second choice or if they aren't suitable you start the process again. You might not agree with the process but you provide no information to support your view that it was 'irregular and chaotic' other than it wasn't done in the way your experience suggests it should be done. Of course the owner has the ultimate say unless he devolves the decision to someone else. Attansio has plenty of experience hiring high level people for key roles including people involved in coaching sports teams and he's paying the bill. Why wouldn't he be involved in the final decision.