Ken hardly needs the command; his eyes barely seem to be able to stay open, with all things taken into account. "Don't leave, Kakipi," he mumbles, though by all appearances he drifts off so quickly after the words leave his mouth that either he didn't expect an answer, or he couldn't maintain consciousness long enough to hear one.

It's hard to know if Ken wanted Chikusa to stay with him physically, or if he was worried Chikusa might be slipping away from him mentally again. Honestly, knowing Ken, he probably meant both. He's not likely to get either, but at least he's asleep (or unconscious; it's a fine line to draw right now) and won't know it.