If she had been attacking the officer physically, maybe I could see it, but it doesn't say that that was the case (of course, I didn't click the link, so I might be missing something). The fact that she was pregnant should have prompted the cop involved to resist using the stun gun, though. He's a cop, after all...he couldn't restrain her himself?
I'm sure she'll sue, and I'm equally sure the judge won't throw it out; how often does that happen, after all, even with ridiculously less substantial claims ?