His point is that poorly made anti-virus software makes your computer even more vulnerable, because of the deep access that type of software has. Unfortunately, many of the most well known options seem to be poorly made.
http://arstechnica.com/security/2016...mail-or-links/
Tuesday's advisory is only the latest to underscore game-over vulnerabilities found in widely available antivirus packages. Although the software is often considered a mandatory part of a good security regimen—on Windows systems, at least—their installation often has the paradoxical consequence of opening a computer to attacks that otherwise wouldn't be possible. Over the past five years, Ormandy in particular has exposed a disturbingly high number of such flaws in security software from companies including Comodo, Eset, Kaspersky, FireEye, McAfee, Trend Micro, and others.