I think the logic of not shorting in a dull market comes from the fact that in markets that are trending up, pull backs are usually on smaller volume and don't drop as much so you can easily find yourself getting fried on the next up tick. However there has been no volume in the up ticks today so really it's a 50-50 proposition.
FYI, never take a position unless you're very sure of it. You of all people should know about trading discipline 77 will be a big stretch given the lack of volume but I hope it works out for you.