Bear in mind I despise Celtic in my response to that.
To point out Celtics failings in that season is a mere distraction from the actual debate. It is a wider debate around Rangers actions at that time.
The whole 'sporting advantage' debate is a red herring for me anyway, in sport you can forever talk about the ifs buts and maybes and how much of a direct impact having De Boer or whoever in the team may have had.
For me it's simple, was a form of deception and contravention of rules used to sign football players to compete for a league title. If so, there is a huge argument to say that title is void.
There are many real life examples of teams being disqualified from competitions for administrative errors on a hugely smaller scale than this.