No problem. Attaching to the gas plug only means you don't have to remove the tube, but since you remove the poppet in either case, I don't see any trouble. I've also seen people unscrew the pressure relief valve and put the blow-off/airlock there.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk