What the gentleman means is: there are no viruses out there for OSX, so you don't need anti-virus software to protect against 'm. Any "OSX anti-virus" software on offer is bogus.
Trojan Horses are another matter, though. Trojan Horses can install all kinds of nasty software on your Mac. BUT ONLY IF YOU CLICK THEM!
So always be careful with what you download and what you click to open or install*. Just as on Windows. No different. YOU decide what runs on your machine and what doesn't.
Not everything is what it looks like.
*pay attention to the configuration of the Preferences of your browser(s). Don't let the browser auto-run just anything it encounters on the interweb, and don't visit the naughty websites unless you have some 'extra protection'. Or you'll be very likely to catch something.