Q wouldn't be terribly helpful in being protected either.

"I don't mind being catapulted."
"How soon we've forgotten the chimney debacle last week."
"That wasn't Sherlock's fault. I'm wearing the proper shoes this time."

I suspect it's people not as familliar with the series who think that Q is an initial and not short for Quartmaster, the way Bond implies M is short for something in Casino Royale.

I do also wonder if people were also inspired by Mallory becoming the new M as it being somewhat canon that a Q name should be given to the Quartermaster.