I knew about this "twist" before watching the episode, so when it got to the scene where Stamets basically said he was retiring I thought "oh, that's why." Lorca is enamored of the spore drive and seemed genuinely driven to keep using it to explore after the war is over.
Or Lorca has another use for the drive that is unknown to everybody else, and needs it perfected for said use. Every time we've seen him act in a manner that could be described as "evil" or as nefarious has been to protect the drive, and keep it under his command.
I think it is a valid reading to see Lorca is a manipulator and an opportunist. I think he's an incredibly skilled con man when he wants to be. Note, this doesn't make him evil. Sinister perhaps, but that undertone has been present all season, in a variety of ways.
Saru and Burnham figure out a way to crack the cloak, but it will take a ton of readings from a ton of angles. What is Lorca's solution? The multiple jump pattern. It's crazy, and maybe brilliant. It works, the cloak is cracked, Starfleet scores a big win. But... Lorca also gets all of that Spore drive mapping data.
The same thing in the later discussion with Stamets. People keep saying "Lorca can't read minds!" or "He would have had to bring up the idea of one more jump for it to be a manipulation". You're all wrong. Lorca doesn't just congratulate Stamets, he explicitly brings up the fact that Klingons are coming. He knows Stamets, what drives him and motivates him. He can't know that Stamets will offer another jump, but he suspects it is likely if Stamets knows the crew is in potential danger. Lorca offers just enough information to tempt Stamets, hoping that his reading of the man will lead to the outcome he wants. I suspect if it hadn't worked, something else would have come up. Some other threat, some other piece of urgency.
My favorite aspect of the Lorca character so far is that he is somewhat inscrutable. You can absolutely see the potential that he may have manipulated people into what he wants, and mucked about with the final jump. But that isn't the only available reading of the situation. You're left to wonder, to see the hints of both tremendous heroism and potentially distressing darkness in the character. Every action he takes could be for the greater good, or for his own personal gain. The two aren't even mutually exclusive! He could mean every word of the Stamets conversation, for example, but still take advantage of Stamet's choice if he saw some gain.
People aren't always good or evil. They have the potential to be either or both in different measure. The greatest amongst us often seem to be those who can be both heroic and ruthless, self serving and gracious, kind and yet utterly violent. That people can do reprehensible things for good causes, or amazingly benevolent things for the most despicable ends is not in question. Lorca walks that line really brilliantly so far. I, as an audience member, am left to ponder his every action, his every decision. To see both the good and the bad in the man. He's utterly compelling, and I actually dread the day that the show decides to water him down and establish that he's "good" or "evil".