[newguy357]

So, let's see... hot gasses somehow are affected by a "drag force"... in a vacuum that is almost indistinguishable from the rest of interstellar space, say 1 atom per stere(1 cubic meter) to be really generous, but the much more plentiful and gravitationally active "dark matter" does not even collide with other dark matter???? So what is this "Drag force?" Magic?

You said it yourself, later in your post: at the temperatures mentioned the luminous gas should be largely ionized. The two approaching clouds would then most definitely have significant "drag" due to the em interaction.

[newguy357]

at the temperatures mentioned the luminous gas should be largely ionized.

I retract this statement. It's late.