There's no difference between the torque you can produce on a freewheeling vs. a fixed gear singlespeed. In either case, it's almost always less than what you can get out of the small ring on a triple. Ergo, proper quick releases work perfectly fine on fixed gears, so whether the bike can coast or not makes no difference at all.

*Edit: Sorry. It doesn't make no sense, just implies something of a myth.