That's because he didn't have the Sharingan yet. I'm sure that if he had the Sharingan at the time, he would've jumped straight to MS.I agree that nothing can stop Sharingan plot pulls.
But Sasuke who had emotional trauma as well as Itachi and Obito didn't went straight from 1-2-3 tomoe to MS. He even couldnt awake 2 tomoe instantly despite his trauma
.
The massacre made him awaken it for the first time.