Is there anything in the world that couldn't use some more miniguns?Maybe Weaver is actually one of the good guys or at least a rebel faction of machines that is sent back in time to keep skynet from getting too powerful too quickly, you saw how she essentially went into that building and wiped everything out after finding out that they were stockpiling that metal.
That's one possibility. Another is that she heard the part of the recording that said they'd been compromised, and decided to clean house to dry up the trail.
The two aren't mutually exclusive, she'd interested in keeping her own operation under wraps no matter what her end goals were.
It's also possible that Weaver wants to gain personal power by manipulating John Henry just as Jesse is attempting to manipulate the young John Connor.
Personally, I think that the show needs more miniguns. This episode was fairly slow, overall, and miniguns could have made it much more exciting.
I didn't think so.
Also, the IGN TV reviewer gave this episode a 7.8. I thought that was a little generous.