I don't think TPTB were deliberately trying to cancel SGA - especially because Mallozzi & Mullie, the current showrunners, thus far are not signed onto SGU. So they would've been possibly writing themselves out of a job...(maybe that wouldn't be such a bad thing. M&M are, um, they could be more talented.)

Even more than Jewel Staite being young, greyias points out that she's Jewel Staite - the writers think her fanboy cred and perky smile is reason enough for her presence. I don't think Keller's entirely useless - she's definitely done some real medicine - but she's done relatively little that any reasonable skilled physician or surgeon couldn't do. And she's got all those negatives against her that haven't been countered. Yeah, I don't understand how she got her position, as opposed to a thousand other doctors on Earth...

Oh well. Best we can do is hope for more team and less Keller, in the coming eps!