First, Room Lighting could sort of do this using the "preset off" feature, though I'm not sure about fading. I also wrote a custom app that, among other things, can dim lights before turning them off if you are interested: [RELEASE] Lights on Motion Plus (dim before off, remember individual bulb states, etc.)
That being said, I'm not sure I understand the problem with the rule. Doing a "Set level" to 0 will normally turn off a light, baaiclly equivalent to "Off" except it will normally respect a specified transition time. The switch (on/off) and level (dim level) attributes are tracked separately, and you will therefore normally not see "level: 0" reported at all, including when the light is off. I'm not sure if any of this describes your problem or if you're using an odds driver that behaves in a different way. Or maybe you just need a way to cancel? In that case, another "Set Level" normally does that (to the previous level, I suppose, which you'd have to have saved? Thisnaeema like it should be the same no matter how you approach this automation).