If that was the case, in a match that that particular one that has so much "history", that person should not have been appointed to officiate.
Yes, you’d think so.
But the problem in Scotland is that the whole football environment is so dominated by Rangers and Celtic that pretty much every person involved in Scottish football from the CEO of the SFA down to the tea lady at the Civil Service Strollers is either a direct fan of one of the Old Firm, or has an allegiance whilst being a fan of another team
If you don’t appoint refs in that category you’re picking from a very small pool of refs who may just not be good enough