It wasn't that Barty didn't trust Theo, he did. But every hour he spent with Evan showed him that there was so much in life they took for granted and didn't think anything of that was hocking or surprising to Evan. Barty knew his memories inside out, obviously. But Theo's? Hell, if it were the other way around, Barty doubted he would have been able to completely properly label them for warnings.
"Sleepless nights, here we come," Barty joked, though it was partially true. Depending on how many memories Theo left, how many nightmares Evan had, how much thinking kept him awake, how long he had to sleep on the floor, sleep wasn't high on his list. But Barty had worked that way often over the years. He didn't need the most sleep to operate at full function.