Like I said apparently Microsoft finally got it's act together with Windows Essentials but don't rely on just that. At least load Malwarebytes as a backup to see if anything got through that Essentials missed and if you want realtime browser protection load Malwarebytes Anti-exploit.I know absolutely nothing about "heuristics-based scanners" but I should tell you it took more than an hour for Essentials to remove the Trojan it detected. It posted a two page listing of items it found and removed. The bottom-line for me is the Trojan is reportedly gone and my computer is working fine.You were probably talking to an Microsoft trained IT tech, you wouldn't believe the BS Microsoft feeds them.
Never thought I'd hear myself say it but Windows Essentials did very well in independent tests where as Windows Defender did terrible. While it's able to "scrub" an infected system it can leave traces of the malware behind that could cause problems. What Essentials mainly lacks is a relatively new detection feature, heuristics-based scanners but then again many only include that feature in the for sale versions. Two problems with heuristics-based scanners is length of time to do a scan and number of false positives so that technology is a trade off.
Add Malwarebytes Anti-Exploit Free, it runs when you open your browser and is a zero day malware protection program (App to you Windows acolytes)