More generally I think we should campaign to get most McAfee stuff classified as some kind of badware: scareware, bloatware, nagware etc.
I do very little computer support (only friends and family and the occational coworker) and still I have solved a number of cases lately just by uninstalling anything McAfee related I could find.
Between drive by downloads and blocking internet access if you don't pay for protection it easily gets a place on my badware list at least.
Yeah I'm sure someone could unblock it, but I doubt they blocked it in the first place on purpose: OSM must be in some default list when McAfee Web Gateway is first installed, and that's probably the root of the problem...
Please don't spread this kind of FUD – even the article you linked to is much more measured. It's pretty silly to imply that there was any corporate action on behalf of Google aimed at vandalising OSM at the same time as the were sponsoring their annual conference.
I agree with your criticism, but I don't think sponsoring a conference is definitive proof of good will or alignment of interests. Some of the companies that sponsor Linux and FOSS conferences also take actions, for example in court, that are against the interests of those communities.
Edit: I'm reminded of Thomas Schelling's notion of "incomplete antagonism" :-)