There are two versions of this softlock: finishing phase 3 before the title drop finishes and finishing phase 4 before he starts to say his first line ("No...no, not yet!") Doing either of these puts the game in a state that the triggers at the end of 3 and beginning of 4 can't handle. If you see an orange and a white healthbar at the bottom of the screen then it has softlocked and will never fade out after finishing phase 4. Avoid finishing phase 3 until you can see the healthbars, and avoid finishing phase 4 before he starts to speak.

Note that this may not be 100% accurate as the softlock isn't fully understood yet and further testing may be needed.

2.0 UPDATE: The phase 4 softlock is still present, however it seems the healthbars appear even if the game has not softlocked. Just make sure not to kill him before the healthbars appear.