Might finish this sketch later it depends if I get time for it :) <3
On the Knock Out thing, couldn't it be said that even while he's "reactive" his reactions are a tad overkill, and indicative of a desire to see the other party suffer for his vindication? Also in Plus One, he DOES terrorize June and Fowler, chasing them around the trainyard and "hide and go shriek". And with Smokey, he still comes within inches of gutting him. While perhaps not physical sadism, he still delights in the terror he inflicts upon others, often for his own satisfaction.
I feel like this is probably a power thing more than a sadism thing, actually. Knock Out clearly enjoys having power and influence over other people— I think the way he curries favor shamelessly with both Starscream and Megatron and his partnership with Breakdown stand as testament to this.
Knock Out is the smallest and least physically powerful of all the Decepticon officers we meet in the show save Airachnid, and his weakness and vulnerability are something that Megatron deliberately uses against him to control him. Beyond that, Megatron obviously doesn’t value his medical or scientific contributions— the only quality Megatron values in anyone is physical strength in slavish obedience to himself. After Breakdown’s death, Knock Out loses the physical power he possessed by proxy, and therefore all value in Megatron’s eyes.
So we’ve established that Knock Out is vulnerable, craves authoritative power and lacks the physical power to take it, and that his position among the Decepticons is insecure. Couple that with the fact that he can be very petty and vindictive, and it honestly doesn’t surprise me that he trolls and plays with people who are vulnerable to him. He probably does get a thrill out of feeling like he’s feared and like he’s in control, because he’s not on the Nemesis.
But again, I think the fact that he doesn’t hurt these people when he has the opportunity to speaks just as strongly as the fact that he trolls them and plays games like he’s going to. Yes, he comes very close to gutting Smokescreen— but in the end he doesn’t, even though I’m sure it’d be just as easy to slice him open as to utilize the phase shifter. Not only that, not hurting people it would be easy for him to hurt is a consistent characteristic of his across three seasons— I cite again the way he treated Starscream in “Shadowzone”. A sadist would have delighted in Starscream’s pain, but Knock Out repeatedly tries to get him to sit down and recover.
To me, sadism is about the desire to inflict pain and physical harm on another person for pain and harm’s own sake, and I just don’t think Knock Out feels that desire.