Maybe its to improve the the timing for the two feeds ( soon to be five feeds Its must be pretty good playing out 5 different idents for local channels when there start broadcasting?)
Since the affiliate deal in 2012, STV has broadcast most International games - only opting out for the STV Children's Appeal, and this coming Tuesday for Scotland Debates.
STV isn't showing the England game on TV. It's instead showing an election debate show. It is apparently going to offer the game on its website.
Can't see this as a good move to be honest. I imagine there will be a theory that most people in Scotland will want to watch the Scotland game, so therefore the natural audience wouldn't be there for the England game. However, the Scotland game will be on pay-TV and it's not a good idea to get people in the mindset that you can't rely on the channel for a type of match, they will just go to ITV by habit in future.
If STV was saving any money by not showing it fair enough, but they're now in a new affiliate deal and it's on the website, so it can't be that.