Without a doubt, my favorite line in all the LSAT lessons🤣

I'm cooked

If i understand you correctly, you're confused where/how he got the /Upset→/Label. He got it from the application. He was showing how the application was mistaken in translating the principle. The principle was Upset→Label (contrapositive: /Label→/Upset). The application just slapped negations on to both the upset and the label and attempted to justify its conclusion, when it actually made in error in its logic (it forgot to contrapose). JP used their incorrect translation to show how it was incorrect in those answer choices.

Was looking for someone else with this thought lol.

This is right, but if you ignore infer and look at the rest of the answer it is still not correct. The answer gets it backwards. The stimulus says that because one thing is NOT happening, then it can conclude that the only other probable explanation will happen. The answer choice (B) says that because this probable event WILL happen, then the only other probable explanation will not happen. The answer choice simply gets it backwards which is why the rest of the answer is incorrect.

Stimulus: Alt 1 will not happen → Alt 2 will happen

Answer B: Alt 1 will happen → Alt 2 will not happen

I think this is a good explanation. The conclusion is what is ultimately being said. Everything from the stimulus is flowing into the statement that superconductor development will "probably improve industrial productivity." The analogy is supporting this meaning that it is our conclusion, even if the word probably sounds uncertain.