Sadly he didn't. And just what is it with the command structure in these films? Scotty becomes CE out of nowhere in the first film, and he doesn't have a replacement so that the 17 year old navigator has to take over? Geez...
I guess it makes a little more sense than a guy going from a cadet on academic suspension to full on Starship Captain in about a week.
I love how the music gets ominous after Kirk tells him that and Chekov makes an overexaggerated gulp like he knows he's doomed
Scotty illegally beaming aboard the ship (which he was never assigned to) and becoming Chief Engineer of it is even worse. Where was the actually assigned CE? Why was Scotty more qualified than that CE? And Chekov switches department and job. Scotty didn't have a replacement? Who replaced Chekov? Is Chekov's whiz so wasted in his Navigator duties that everyone can replace him? But he is the only one able to replace Scotty in engineering?
CE Olsen was flash fried on the Romulan drill platform. He was no longer "available". Acting Captain Kirk made Scotty CE when he took command. As a Lt. Commander, I'm sure Scott was the ranking Engineer on board no matter how he got there. Favoritism. Just like when LaForge became CE in TNG, even though the Enterprise was shown to have an abundance of engineers ranking him. Chekov was replace by the bald lady. To my knowledge she's the only one who has.
Just a random thought I just had, while Chekov being assigned to a redshirt was mostly used for laughs and they needed a main character to replace Scotty, do you think the writers possibly did it as a nod to Chekov not being on the bridge in Space Seed?
Since one of the Treklit explanations is Chekov was in engineering during "Space Seed" and the one of the writers is a Treklit fan, I wouldn't be surprised.