Intel doesn't have much of a foundry business -- they build for themselves -- so if anything this increases competition in the foundry business, if Intel follows up by letting GloFo customers use Intel's best fabs.
http://www.businesskorea.co.kr/news/articleView.html?idxno=6...
And if we look at the entire chip-making business, instead of the narrow foundry-for-hire category? Or consider the possibility of Intel expanding (not just buying) into the foundry business?
Also, note that anti-trust law isn't about the possibility of future expansion. Intel already tried to enter the non-memory foundry-for-hire business and failed.
Mind you, I've been at 2 organizations that have purchased chips from foundries, and we turned down both Intel and IBM's offers. I'd love to see more competition in that industry, and Intel buying GloFo will add to competition on the high end.