Pretty much. People from Glasgow support teams from Glasgow generally. Up North there's a serious amount of oil workers so maybe that's part of the reason. Scottish football isn't on TV much any more so that also helps too.
We don't have an issue with Scottish people supporting Scottish teams outside of their home area as there's absolutely no glory to be hunted people usually either support some s**** Scottish home team or like Liverpool or Brazil or something. Mostly Man Utd, Liverpool, Arsenal.
Anyone remotely Irish in any way will rabidly support Celtic though. Weird folk.