The instructions on bug bombs (foggers) say to turn off all pilot lights before setting the off. But what is the real danger of leaving the pilots on.
I have a one bedroom apartment with a gas stove and a gas floor furnace. If I shut off the gas to the stove, and covered the vent of the floor furnace and kept the pilot lit, how great would the danger of the fumes igniting be??
The real danger is that the fumes will ignite, isn’t it?. 
I imagine if you cover the vent, either
a) It seals it, no oxygen gets in and the flame goes out
b) It doesn’t seal it, fumes get in anyhow, and
c) Opal ends up reading your eulogy.
There’s a reason for the warning on the label:
http://unclestupid.com/article107.html
http://www.sptimes.com/2002/05/21/Hillsborough/Explosion_raises_spec.shtml
This sort of thing happens very regularly. Don’t try to repeat it.