what, no
add-ons have no such possibility and backdoors, trojans and viruses cannot execute inside a .zip, nor can torque even execute stuff like that anyway. I'm also quite sure it's not possible for the antivirus to even detect a trojan inside of a .zip. The worst an add-on virus can do is edit blockland's folders.
avast is probably detecting blockland as a threat because it connects to the internet, avast is known to be a stuff antivirus anyway
He's talking about an add on that has a executable that can be infected.
Most anti-virus programs detect false positives, which is why I never download them, not just the only reason, these programs want to work better if you pay for them, some can ruin performance (avg consumed my RAM somehow), or maybe even do damage to the computer. So I stick with default computer anti virus stuff.