It's not the drinkers they are targeting, it is the tap space. Uneducated business owners will see $56 for a macro "craft" keg or $145 for your typical craft keg, see some dollar signs and buy the cheap-o keg. You favorite beer hotspots probably won't fall for such nonsense but places like stadiums, large chain restaurants or other corporate entities that don't understand craft beer culture and/or typically only offer a token craft beer or two in their tap lineup.
Really probably won't (immediately) affect you favorite local beers either. The impact will felt by MillerCoors own sudo-craft line (Blue Moon) who may have to engage in a price-war to keep their tap space, and also by the larger craft brewers such as Sierra Nevada, Sam Adams and New Belgium who currently occupy the token-craft-beer tap space at the places that don't offer large beer selections.
You are correct that beers like Blue Moon can act as gateway beers to introduce people to the craft beer world, which is why I typically don't begrudge them to much. But make no mistake, while MillerCoors has been actively trying to expand their craft beer line, InBev is still much more interested in collapsing that market.