This sounds familiar, hmmmm....
Yes, it sounds just like the code found in the Steam files back in June.
I'm sure this is not at all related or a reaction to MS' semi dropped sharing features that's been promised to make a return.
Not sure if sarcasm or not, either way I doubt Valve leapt into action and added code to Steam for sharing within a month of Microsoft's announcement considering they would have had to flesh out the details and quarks before ever sending the feature list to their programming department (what I mean by that is Steam showed signs of game sharing back in June, only a month after MS announced game sharing on the Xbox One). I'd be willing to bet that Steam had plans for sharing in the works long before Microsoft ever announced it as a feature for the Xbox One. Doesn't mean Steam was the first with the idea, it simply means they came up with it on their own and didn't copy it from another company.
We all know that whatever Valve or MS tries to do, they have to work with game publishers to get on board with it. Who knows, maybe the connection check every 24hrs was a way to get publishers on board with MS' sharing/trading/etc ideas. Now that there will be no check, MS may not have leverage with the publishers and the sharing plans have to change.
Valve already has that solved though (dealing w/ publishers), by reading the FAQ this sharing system will not work with any game that requires additional access codes or subscriptions (and only those games.....all other games it will work with), and it relies on Steams virtually constant connection. If you switch Steam to offline mode you will not be able to access a friends shared library (only your own local library) so you can't cheat to system using offline mode.
Valve already holds a very dominant position in the PC digital distribution market, I doubt any publisher is going to not put their game on Steam strictly because of the sharing system. After all, it only allows one person at a time to access their game, why would it matter if person A or person B had paid for it if they both need to buy it to play at the same time?