Yes it was completely silly to have her on the volcano mission and insane to beam her onto that transport rather than a security dude. But it was also good to see them giving the women something to do other than open hailing frequencies. It doesn't make a huge amount of sense but it's better than the alternative.
When are we going to have a woman villain?
In the comics both Zahra and Rand take on the roles of security, although I favour keeping Rand as Kirk's yeoman because it gives her more of a connection to him and to the action. At the moment, they've glossed over why she is a yeoman at all.
Admiral Marcus should have been Carol's mum. Anybody who has watched the Manchurian Candidate could see a parallel. To late now though - nothing but male admirals in this reality. Buttlerfly Effect dontcha know?