It's always like this with SG, it may be this or may be that

Noji's fears that her innocent boy might fall prey to lustful cougars seem like a very weak and hastily concocted excuse for her over proportional concern.
I'm more inclined to think that she's afraid that Sherlock will connect the dots between her, Katie, Amber, Emilia, the Zanes, the mystery of Nami and Nika's origins, all that weird gathering looking like a boring ladies club but clearly being something more than that and start digging. She knows how stubborn he can be.