If it's rated for use as a switch, sure you can use a breaker as a switch. I have a Tyco breaker that's rated as a switch (looks like a toggle switch) that I bought because when I was planning a FLARM install that was integrated with an LX8080 Simple/V5 I wasn't sure whether the LX delivered switched or unswitched power to the FLARM. As it turned out it delivered switched power so the breaker is on my shelf rather than in the glider. The glider has two aircraft spec breakers on the panel and one built into the battery box. My glider no longer has any master switch as all the avionics have their own built in on/off switches so the only thing the master switch did for me was to present me with the possibility of turning everything off in flight by accident.