Microsoft Security Essentials Correlation

So Microsoft Security Essentials failed to gain a certification on a recent, well-known  AV test.

That's unfortunate, since it's free, without subscription, and provided by those that make Windows.

Meanwhile, I saw this article, basically saying that the people behind the program AppRemover saw that on 150,000 or so computers, most of them were running Microsoft Security Essentials.

According to the CNET article, AppRemover is using it's data to claim that Microsoft Security Essentials is a “global leader in security suite market share.” 

There's a weird correlation, though. AppRemover is a program that, among other things, uninstalls security software. Presumably, the people using AppRemover have a reason for doing so, such as uninstalling antivirus software that they didn't want. If AppRemover is reporting that a majority of computers that had AppRemover used on them already had Microsoft Security Essentials installed, and the user is running a program that removes antivirus software, it would seem to correlate that the majority of people who use AppRemover on a computer with antivirus software already installed (as reported in the article) are using it to remove Microsoft Security Essentials more than the other antivirus suites?

Either that, or the computers measured have more than one antivirus program installed.