Any way to "right-click->open" application using application launcher or AppleScript?
You could create an Automator service with a Run Shell Script action like this:

for f; do
  q=$(xattr -p com.apple.quarantine "$f" 2&gt; /dev/null)
  if [[ $q ]]; then
    xattr -d com.apple.quarantine "$f"
    open "$f"
    xattr -w com.apple.quarantine "$q" "$f"
  else
    open "$f"
  fi
done


Set the input type to files or folders (just folders doesn't seem to include application bundles) and set "pass input" to "as arguments".

Or in Alfred 2 you could add a File Action trigger and connect it to a Run Script action like this:

f="{query}"
q=$(xattr -p com.apple.quarantine "$f" 2&gt; /dev/null)
if [[ $q ]]; then
  xattr -d com.apple.quarantine "$f"
  open "$f"
  xattr -w com.apple.quarantine "$q" "$f"
else
  open "$f"
fi


If you want to keep Gatekeeper enabled but make it ignore some applications, just run something like xattr -d com.apple.quarantine /Applications/SomeApp.app.