...when it comes to advertising, search engines are not bound by the First Amendment's free-speech guarantees.
I agree with the decision to a point, but some aspects of this that might limit advocacy on the web make me uneasy.
To cite some parallels in other media... Suppose all TV networks decided not to run campaign ads for the party not in power. Advocacy ads in newspapers have from time to time been a significant part of political reform.
Any constitutional lawyers around to tell us how that line is drawn?