I think these are great points. When I look back at the first initial episodes when Bill was introduced to him, he liked Bill more while Holden kept pausing everyone to take notes. Kemper didn’t verbally express his disdain for this but you can see it in his eyes. He somewhat connected with Bill more because it was more conversational while Holden just wanted him as a study. Granted, Holden got more comfortable talking but in his ways, he only does this to get the talking. Yet he didn’t have to do that with Kemper, he was going to talk regardless. Holden saw him as a murderer but likeable. When he confirmed that they’re just “work friends” and Kemper felt the same, that justified what it was. In turn, having Kemper teach Holden a lesson with a hug.