Except the video I linked, they admitted they’d lost the vacuum after ignition, so it was just another staged dumbshow.
Again, in the “endless absolute vacuum of ‘space’” there is no ignition, only instanteous skin ripping off your face and dispersion of molecules.
I’m not talking about the video, I’m asking if you accept the principle that gas expanding from a chamber has a maximum velocity, and therefore, a maximum flow rate through an orifice.