Yeah, I thought that too. I was thinking along the lines that Traya knows G0-T0 is a droid, and she knows anything biological would be corrupted on Malachor, so he may suspect droids. But its more that she would expect assasination, and would therefore seek to be where G0-T0 is not.
I'm a tad confused here, because I thought Traya doesn't know about G0-T0's powerbase, and therefor won't know about the HK units. This will turn them into G0-T0's secret weapon, seeing as she cannot sense them with the Force, cannot see them, cannot see their coming in the future, and won't even know of their skill until it's too late.
HK-50 droids were G0-T0's secret assassin force. He deployed them personally, meaning that few would know of their existance. Traya doesn't know they exist at the beginning of the Kaggath, and probably won't know G0-T0 has them in time for an attack to be avoided.
Besides, seeing as Malachor is Traya's source of power, a place she is drawn to, and the center of basically all of her powerbase, leaving it seems like a horrible idea if she's trying to avoid assassination. It leaves her open to assassination attempts by the Ubese and Zhug Brothers, as well as the Exchange.
Even so, getting to the Trayus Core could be tricky. Unless the HK droids literally drop in from above... possible? With neural dampeners and stealth technology etc.?