Tuckerization

The key to the identity is in the line "I can't abide zombies. They ruin everything." (In an earlier scene, he slaps a table, red faced and angry; couldn't quite fit in "Kruschev-like" as I don't know how many people younger than ourselves would even get that reference.)

“Now, don’t get me wrong, Dalia,” Doctor Jack continued, turning his attention to Truman. “I still hate ’em, deep down. No sir, I can’t abide zombies. They ruin everything. There used to be so many different kinds of people: young ones, old ones, black, white – all wanting different stuff.” He pointed an accusatory finger at Truman. “Then they just turned into this. Can’t buy stuff. Can’t do anything. Heck – teach ’em a few tricks is the best I can do, to bring in some folks and their money.” He brought down his finger, then raised his hand to run it across his bald head and through his thinning hair. He sighed so long and deep that Truman could almost feel sorry for him, if he hadn’t just tried to heap all his shortcomings and disappointments on Truman. “Some days it doesn’t hardly seem worth it. Just should go try a new line of work.”