They don't have to block access to Google. They just have to make Google a tenth of a second slower. The user won't notice that much, but Google knows how many millions of dollars it loses when its pages load slower.
Or they can just remove all google's ads and replace them with their own.
This is what BT (the UK's effectively monopoly phone co) did.
The introduce a system (phorn) that monitored all your browsing and replaced the ads with ones by it's customers more targeted to your 'interests'.
It got found out when it removed all charity's ads following an earthquake and also replaced all the ads on a sesame street type kids site with ones based on the father's browsing the night before!
This was illegal but somehow the government never got round to prosecuting them - in spite of the EU telling them to.
