He'd wipe Corliss' memory because Corliss saw his memories. They're not friends, so why would he want Corliss walking around knowing secrets about Temrash? He doesn't admit guilt because he's trying to get around Corliss to talk to Reven, and doesn't want Reven to know he used unscrupulous means to find him.
He desn't expect to gain Corliss' friendship again, but Corliss isn't the top dog in the rebellion. as far as he knows, Myitt might still vouch for him with Reven if Reven wants someone to do it. Though right now, he's considering just allying with the rebels instead of actually joining under Reven's command.